The captors gave the two governments until 8 December to meet their demands, Aljazeera quoted a statement delivered with the tape aired on Friday.

Two Canadians, one American and a Briton are being held.

The Canadians were shown eating from plates of what appeared to be Arabic sweets. The Briton and American hostages were shown talking to the camera but no sound was transmitted.

The two were calling on the US and British governments to withdraw from Iraq, Aljazeera said, quoting the kidnappers' statement.

German hostage

Meanwhile, the mother and sister of a German woman taken hostage in Iraq have called on her kidnappers to show mercy and release her in an appeal shown on Aljazeera on Friday.

"We beg of you - be merciful and graceful with my daughter and release her and her escort as soon as possible," Ingrid Hala, mother of the abducted Susanne Osthoff, said in the appeal. 

Susanne Osthoff has been held in
Iraq since 25 November

Osthoff, a 43-year-old archaeologist, disappeared a week ago. Earlier this week, her kidnappers said in a videotaped message that they would kill her if Germany did not end all support for the Iraqi government.

Germany helps train Iraqi forces outside the country but has ruled out sending troops there.
   
An image from the tape, delivered to Germany's ARD public television in Baghdad, showed what appeared to be Osthoff and her driver sitting on the ground surrounded by three armed, masked men.
  
"We appeal to you to spare the lives of my innocent sister and her escort," her sister Anja Osthoff said. "My sister has lived for a long time in your country and is devoted to it. She brought sick people medicine. She loves Iraq's great culture."
  
It was not clear who had abducted the archaeologist, a converted Muslim who had spent about 15 years working on excavations in Iraq before UN sanctions forced foreign experts out of the country in the late 1980s.