From the opening days of the Iraq campaign in March 2003, there were uncorroborated reports of use of chemical and other unconventional weapons. These reports emerged again with the re-taking of Fallujah one year ago. Thanks to the work of an Italian documentary team, these claims are now in the headlines again—in Europe at least. From the UK Independent, Nov. 15:

The controversy has raged for 12 months. Ever since last November, when US forces battled to clear Fallujah of insurgents, there have been repeated claims that troops used "unusual" weapons in the assault that all but flattened the Iraqi city. Specifically, controversy has focussed on white phosphorus shells (WP) - an incendiary weapon usually used to obscure troop movements but which can equally be deployed as an offensive weapon against an enemy. The use of such incendiary weapons against civilian targets is banned by international treaty.

The debate was reignited last week when an Italian documentary claimed Iraqi civilians - including women and children - had been killed by terrible burns caused by WP. The documentary, Fallujah: the Hidden Massacre, by the state broadcaster RAI, cited one Fallujah human-rights campaigner who reported how residents told how "a rain of fire fell on the city". Yesterday, demonstrators organised by the Italian communist newspaper, Liberazione, protested outside the US Embassy in Rome. Today, another protest is planned for the US Consulate in Milan. "The 'war on terrorism' is terrorism," one of the newspaper's commentators declared.

The claims contained in the RAI documentary have met with a strident official response from the US, as well as from right-wing commentators and bloggers who have questioned the film's evidence and sought to undermine its central allegations.

While military experts have supported some of these criticisms, an examination by The Independent of the available evidence suggests the following: that WP shells were fired at insurgents, that reports from the battleground suggest troops firing these WP shells did not always know who they were hitting and that there remain widespread reports of civilians suffering extensive burn injuries. While US commanders insist they always strive to avoid civilian casualties, the story of the battle of Fallujah highlights the intrinsic difficulty of such an endeavour.

It is also clear that elements within the US government have been putting out incorrect information about the battle of Fallujah, making it harder to assesses the truth. Some within the US government have previously issued disingenuous statements about the use in Iraq of another controversial incendiary weapon - napalm.

The assault upon Fallujah, 40 miles from Baghdad, took place over a two-week period last November. US commanders said the city was an insurgent stronghold. Civilians were ordered to evacuate in advance. Around 50 US troops and an estimated 1,200 insurgents were killed. How many civilians were killed is unclear. Up to 300,000 people were driven from the city.

Following the RAI broadcast, the US Embassy in Rome issued a statement which denied that US troops had used WP as a weapon. It said: "To maintain that US forces have been using WP against human targets ... is simply mistaken." In a similar denial, the US Ambassador in London, Robert Tuttle, wrote to the The Independent claiming WP was only used as an obscurant or else for marking targets. In his letter, he says: "US forces participating in Operation Iraqi Freedom continue to use appropriate, lawful and conventional weapons against legitimate targets. US forces do not use napalm or phosphorus as weapons."

However, both these two statements are undermined by first-hand evidence from troops who took part in the fighting. They are also undermined by an admission by the Pentagon that WP was used as a weapon against insurgents.

In a comprehensive written account of the military operation at Fallujah, three US soldiers who participated said WP shells were used against insurgents taking cover in trenches. Writing in the March-April edition of Field Artillery, the magazine of the US Field Artillery based in Fort Sill, Oklahoma, which is readily available on the internet, the three artillery men said: "WP proved to be an effective and versatile munition. We used it for screening missions ... and, later in the fight, as a potent psychological weapon against insurgents in trench lines and spider holes ... We fired 'shake and bake' missions at the insurgents using WP to flush them out and high explosive shells (HE) to take them out."

Another first-hand account from the battlefield was provided by an embedded reporter for the North County News, a San Diego newspaper. Reporter Darrin Mortenson wrote of watching Cpl Nicholas Bogert fire WP rounds into Fallujah. He wrote: "Bogert is a mortar team leader who directed his men to fire round after round of high explosives and white phosphorus charges into the city Friday and Saturday, never knowing what the targets were or what damage the resulting explosions caused."

Mr Mortenson also watched the mortar team fire into a group of buildings where insurgents were known to be hiding. In an email, he confirmed: "During the fight I was describing in my article, WP mortar rounds were used to create a fire in a palm grove and a cluster of concrete buildings that were used as cover by Iraqi snipers and teams that fired heavy machine guns at US choppers." Another report, published in the Washington Post, gave an idea of the sorts of injuries that WP causes. It said insurgents "reported being attacked with a substance that melted their skin, a reaction consistent with white phosphorous burns". A physician at a local hospital said the corpses of insurgents "were burned, and some corpses were melted".

The use of incendiary weapons such as WP and napalm against civilian targets - though not military targets - is banned by international treaty. Article two, protocol III of the 1980 UN Convention on Certain Conventional Weapons states: "It is prohibited in all circumstances to make the civilian population as such, individual civilians or civilian objects, the object of attack by incendiary weapons." Some have claimed the use of WP contravenes the 1993 Chemical Weapons Convention which bans the use of any "toxic chemical" weapons which causes "death, harm or temporary incapacitation to humans or animals through their chemical action on life processes".

However, Peter Kaiser, a spokesman for the Organisation for the Prohibition of Chemical Weapons (OPCW), which enforces the convention, said the convention permitted the use of such weapons for "military purposes not connected with the use of chemical weapons and not dependent on the use of the toxic properties of chemicals as a method of warfare". He said the burns caused by WP were thermic rather than chemical and as such not prohibited by the treaty.

The RAI film said civilians were also victims of the use of WP and reported claims by a campaigner from Fallujah, Mohamad Tareq, that many victims had large burns. The report claimed that the clothes on some victims appeared to be intact even though their bodies were badly burned.

Critics of the RAI film - including the Pentagon - say such a claim undermines the likelihood that WP was responsible for the injuries since WP would have also burned their clothes. This opinion is supported by a leading military expert. John Pike, director of the military studies group GlobalSecurity.org, said of WP: "If it hits your clothes it will burn your clothes and if it hits your skin it will just keep on burning." Though Mr Pike had not seen the RAI film, he said the burned appearance of some bodies may have been caused by exposure to the elements.

Yet there are other, independent reports of civilians from Fallujah suffering burn injuries. For instance, Dahr Jamail, an unembedded reporter who collected the testimony of refugees from the city spoke to a doctor who had remained in the city to help people, encountered numerous reports of civilians suffering unusual burns.

One resident told him the US used "weird bombs that put up smoke like a mushroom cloud" and that he watched "pieces of these bombs explode into large fires that continued to burn on the skin even after people dumped water on the burns." The doctor said he "treated people who had their skin melted"

Jeff Englehart, a former marine who spent two days in Fallujah during the battle, said he heard the order go out over military communication that WP was to be dropped. In the RAI film, Mr Englehart, now an outspoken critic of the war, says: "I heard the order to pay attention because they were going to use white phosphorus on Fallujah. In military jargon it's known as Willy Pete ... Phosphorus burns bodies, in fact it melts the flesh all the way down to the bone ... I saw the burned bodies of women and children."

In the aftermath of the battle, the State Department's Counter Misinformation Office issued a statement saying that WP was only "used [WP shells] very sparingly in Fallujah, for illumination purposes. They were fired into the air to illuminate enemy positions at night, not at enemy fighters." When The Independent confronted the State Department with the first-hand accounts of soldiers who participated, an official accepted the mistake and undertook to correct its website. This has since been done.

Indeed, the Pentagon readily admits WP was used. Spokesman Lt Colonel Barry Venables said yesterday WP was used to obscure troop deployments and also to "fire at the enemy". He added: "It burns ... It's an incendiary weapon. That is what it does."

Why the two embassies have issued statements denying that WP was used is unclear. However, there have been previous examples of US officials issuing incorrect statements about the use of incendiary weapons. Earlier this year, British Defence Minister Adam Ingram was forced to apologise to MPs after informing them that the US had not used an updated form of napalm in Iraq. He said he had been misled by US officials.

Napalm was used in several instances during the initial invasion. Colonel Randolph Alles, commander of Marine Air Group 11, remarked during the initial invasion of Iraq in 2003: "The generals love napalm - it has a big psychological effect."

In his letter, Ambassador Tuttle claims there is a distinction between napalm and the 500lb Mk-77 firebombs he says were dropped - even though experts say they are virtually identical. The only difference is that the petrol used in traditional napalm has been replaced in the newer bombs by jet fuel.

Since the RAI broadcast, there have been calls for an inquiry into the circumstances surrounding the battle of Fallujah. The International Committee of the Red Cross (ICRC) has also repeated its call to "all fighters to take every feasible precaution to spare civilians and to respect the principles of distinction and proportionality in all operations".

There have also been claims that in the minutiae of the argument about the use of WP, a broader truth is being missed. Kathy Kelly, a campaigner with the anti-war group Voices of the Wilderness, said: "If the US wants to promote security for this generation and the next, it should build relationships with these countries. If the US uses conventional or non-conventional weapons, in civilian neighourhoods, that melt people's bodies down to the bone, it will leave these people seething. We should think on this rather than arguing about whether we can squeak such weapons past the Geneva Conventions and international accords."

See our last post on Iraq.

See also our previous posts on the history of white phosphorus, mustard gas and napalm use in Iraq, and in Palestine.