Norman Kember, 74, looking strained but calm, appeared alongside his two Canadian and one American fellow hostages in the brief footage aired on al-Jazeera television. It showed the four sitting against a plain white wall. The camera then cut to a close-up of Mr Kember’s passport held by a faceless captor.

In one corner of the video was a date stamp indicating it was recorded on November 27 — last Sunday, one day after the four went missing in west Baghdad. In another corner were two crossed black swords and, in Arabic, the “The Swords of Righteousness Brigade”, a previously unknown group.

The video is the first news of Mr Kember, a retired professor, since his abduction with his colleagues from the Christian Peacemakers Team, one of the last aid organisations left in Iraq. The American and Canadian governments have refused so far to name their nationals.

Friends of Mr Kember dismissed the spy claim as outrageous. “He would never ever dream of doing anything like spying,” Bruce Kent, the veteran peace campaigner, told the BBC. “The last thing he would do would be working for the British Government.”

The Foreign Office said last night: “We utterly condemn the abduction of Mr Norman Kember and his colleagues. The release of this video can only cause further distress to their families.”

Mr Kember’s family released a statement yesterday saying that he had gone to Iraq “for a short time to join a peace group that’s talking and listening to people of all persuasions, believing that dialogue not confrontation should help to bring about conciliation. He feels very strongly that the occupation in Iraq is a mistake.” Security experts said the kidnappers’ failure to make a specific demand meant they might merely be after a ransom.

The video was broadcast just hours after another was delivered to German state television in Baghdad. That one showed a German hostage flanked by insurgents threatening to kill her unless Berlin cut ties with the Iraqi government.

Susanne Osthoff, 43, and her driver were blindfolded and kneeling on the floor, flanked by three masked men, one armed with a rocket-propelled grenade.

The kidnappers threatened to kill both hostages within a “very short time limit” unless their demands were met. The pair were abducted on Friday in Ninawa in northwestern Iraq.

Osthoff, a Muslim convert, archaeologist and aid worker, had been working in Iraq since before the American-led invasion in 2003 and was fluent in Arabic. In an interview last month she said she believed she had become a target for kidnapping by the group led by Abu Musab al-Zarqawi after receiving threats while living in Mosul last summer.

She told a German magazine that American soldiers had taken her from Mosul to the heavily fortified Green Zone in Baghdad where they thought she would be safer. But she apparently returned north to pursue her goal of setting up a German cultural centre in the Kurdish north.

The new surge in kidnappings and killings of Westerners follows a lull of several months during which many left the country or moved into fortified compounds. The only Westerners remaining in Baghdad and the northern areas of Iraq are journalists, diplomats and contractors, with a tiny handful of aid workers.

Earlier yesterday, a third British Muslim died after an attack on a privately hired bus that had taken a group of five British Shias on a pilgrimage to Shia holy sites in Kerbala.

Yahya Gulamali, 60, a businessman from west London, died of his injuries in a Baghdad hospital as the bodies of the two other victims were taken to Kerbala for burial in accordance with their religious traditions.

Jack Straw, the Foreign Secretary, said in London that his death was “terrible”. He added: “They happened to be on the most peaceful of all activities and the most honourable of all activities, namely making a pilgrimage.”

ABDUCTION AND VIOLENCE OFTEN LEAD TO DEATH

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