There are concerns for the fate of five Westerners held captive in Iraq after they appeared on militant videos.
Four peace activists, from the UK, US and Canada, were shown sitting in a row, having been captured on Saturday. The video accused them of spying.
The British government said it "utterly condemned" the capture of 74-year-old anti-war campaigner Norman Kember.
A German TV station said it had a separate video showing a German aid worker with armed kidnappers.
The captors threatened to kill Susanne Osthoff, 43, and her Iraqi driver, and demanded Germany cut ties with the Iraqi government, according to German TV station ARD.
The video showing the four peace activists was aired by Arab satellite TV station al-Jazeera.
A previously unknown militant group, the Swords of Truth Brigade, claimed the captives had been undercover spies working as Christian peace activists.
The US-based Christian Peacemaker Teams (CPT) confirmed that Mr Kember had been taken hostage, along with American Tom Fox, 54, and Canadians James Loney, 41, and Harmeet Singh Sooden, 32.
The group said it was involved in violence-reduction programmes "in areas of lethal conflict around the world."
It blamed the invasion of Iraq for the kidnappings.
The video showed what appeared to be Mr Kember's passport
"We are angry because what has happened to our team-mates is the result of the actions of the US and UK government due to the illegal attack on Iraq and the continuing occupation and oppression of its people," it said.
The four were pictured sitting on the floor.
No demands or specific threats against their lives were made in the tape.
BBC security correspondent Gordon Corera says it could be a positive sign that the hostages did not appear in distress and that there were no gunmen threatening them.
It bears all the hallmarks of a political kidnapping, not one for money, our correspondent says.
The footage had a date stamp indicating it was recorded on 27 November.
Canada says it is doing all it can to ensure the safe return of its nationals.
"I can assure Canadians that there is no more urgent priority than the safe return of our citizens," Prime Minister Paul Martin said.
Susanne Osthoff and her Iraqi driver were pictured with militants
Mr Kember is from Pinner, north west London.
His friend Pat Gaffney told the BBC she was glad he had been shown to be still alive, but expressed anxiety about the future.
The UK Foreign Office issued a statement condemning the kidnappings of the four men shown on the video.
A spokesman said: "The release of this video can only cause further distress to their families at this difficult time."
In Germany, the capture of Ms Osthoff is the first crisis for new Chancellor Angela Merkel.
"We condemn this act in the harshest possible terms," Mrs Merkel said.
Germany opposed the war, but Mrs Merkel said she would continue the previous government's policy of training Iraqi forces outside Iraq.
A group of Iranian pilgrims were also kidnapped in the town of Balad north of the Iraqi capital Baghdad.
Four men and two women were seized on a pilgrimage to a Shia Muslim shrine in Samarra. The women were released several hours later, police said.