The American among four Christian Peacemakers activists kidnapped last year in Iraq was absent from a videotape broadcast Tuesday of the exhausted-looking men purportedly appealing to their governments to secure their release.

Al-Jazeera television, which aired the footage, could not provide explain Tom Fox, 54, of Clear Brook, Va., was not shown.

In Toronto, the co-director of Christian Peacemaker Teams, Doug Pritchard, said he drew some comfort from seeing three of his colleagues on video again.

"The fact that they're still well after more than three months says that the kidnappers have been concerned for their well-being," Pritchard said. "The fact that there are no demands made or timelines set is also hopeful."

But Allan Slater, a Canadian member of the group, said he was disturbed not to see Fox.

"We certainly are hopeful when we see three of our friends alive, but also it's very distressing that we didn't see Tom Fox, and I wouldn't want to hide that because I'm sure it's very distressful for Tom's family and friends as well," Slater told The Canadian Press from Baghdad.

The hostages seen in the brief video dated Feb. 28 were Canadians James Loney, 41, and Harmeet Singh Sooden, 32; and Briton Norman Kember, 74.

The news anchor said the men asked their governments and Persian Gulf countries to work for their release. Al-Jazeera's policy is to silence the audio on hostage tapes for broadcast.

The tape showed the three men sitting in chairs and speaking. One had white hair and a slight beard; the two others had dark hair and full beards.

The previously unknown Swords of Righteousness Brigades claimed responsibility for kidnapping the four workers, who disappeared Nov. 26.

The four had not been heard from since a videotape aired by Al-Jazeera on Jan. 28, dated from a week before. A statement reportedly accompanying that tape said the hostages would be killed unless all Iraqi prisoners were released from U.S. and Iraqi prisons. No deadline was set.

Iraqi and Western security officials repeatedly warned the activists before their abduction that they were taking a grave risk by moving around Baghdad without bodyguards.

Christian Peacemaker Teams has been working in Iraq since October 2002, investigating allegations that U.S. and Iraqi forces abused Iraqi detainees. Its teams host human rights conferences in conflict zones, promoting peaceful solutions.

In a statement issued from its Chicago headquarters Tuesday, the Christian group said "we continue to pray for their safe and speedy release so that they may return to their families and carry on their peaceful work on behalf of all Iraqi detainees."

The group said 14,600 Iraqis "currently (are) detained illegally by the Multinational Forces in Iraq."

"We believe that the root cause of the abduction of our colleagues is the U.S. and British-led invasion and occupation of Iraq," the statement said.

More than 250 foreigners have been taken hostage in Iraq since the 2003 U.S.-led invasion that toppled Saddam Hussein, and at least 39 have been killed.

Among those held is American reporter Jill Carroll, who the Iraqi interior minister has said was abducted by the Islamic Army in Iraq, the insurgent group that freed two French journalists in 2004 after four months in captivity.

Bayan Jabr, who is in charge of Iraq's police, also said he believed the 28-year-old freelance reporter for The Christian Science Monitor was still alive, although the deadline set by her captors for the United States to meet their demands expired late last month.

Three videotapes provided by the kidnappers to Arab satellite television stations identified the group holding her as the previously unknown Revenge Brigades.

The kidnappers have publicly demanded the release of all women detainees in Iraq, but the owner of a Kuwaiti TV station that aired a videotape of Carroll last month said the group provided more specific conditions that he refused to reveal. She was seized Jan. 7 in Baghdad and her translator was killed.

Also held are Thomas Nitzschke and Rene Braeunlich, German engineers kidnapped Jan. 24 from an Iraqi government-owned detergent plant in Beiji, 155 miles north of Baghdad. Kenyan engineers Moses Munyao and George Noballa disappeared in Baghdad on Jan. 18 in an attack on a convoy of the mobile phone company Iraqna. Six security guards and three drivers were killed.