A voice of unassailable moral credibility—we hope—is added to chorus demanding release of the four hostages from the Christian Peacemaker Teams in Iraq.

LONDON (Reuters) - A former Guantanamo Bay detainee has pleaded for the release of peace worker Norman Kember and three other hostages held in Iraq.

Moazzam Begg, a British Muslim held for almost three years at the U.S. detention facility in Cuba, told BBC television late on Thursday that a video showing the hostages dressed in orange jump suits reminded him of his own time as a prisoner.

His appeal came a day after a similar plea to the kidnappers by Jordanian cleric Abu Qatada, who is under detention in Britain for links to al Qaeda and faces deportation.

An Iraqi militant group calling itself Swords of Truth says it will kill the hostages -- Kember, two Canadians and an American -- if Iraqi prisoners are not released by Saturday, Al Jazeera television reported.

In a video broadcast by international media the four men, all members of a Christian aid group, were shown wearing orange jumpsuits and blindfolds and with their hands shackled together.

Begg said he hoped his words would encourage the kidnappers to let the hostages go.

"When we were first granted release by Allah's mercy, we came home to find that there were people who opposed their Government in their brutal war waged against Afghanistan and Iraq and stood on the side of justice. And they were not Muslims.

"It is our sincerest belief that Norman Kember, the 74-year-old Briton, and those with him are amongst those people, the many people, who opposed this war from the beginning and were only in Iraq to promote human rights for the oppressed.

"Just like Sheikh Abu Qatada, we also hope that our words will encourage you to show mercy to these men and let them free."

Muslim scholars and activists from around the world, including leaders of the militant Hamas and Hizbollah groups, have appealed for the hostages to be released.

Foreign Secretary Jack Straw called on Thursday for the kidnappers to get in contact and release their hostages.

Begg, originally from Birmingham, was released without charge from Guantanamo Bay in January this year and sent back to Britain.

See our last post on the CPT hostages, and on the Iraq war.