Kidnapped Briton was quiet pacifist who felt drawn to war zone

But in the aftermath of the war he ultimately could not stop, the dedicated churchgoer and pillar of his community in north-west London had been troubled by a desire to become more closely involved with the conflict. Six months ago, he wrote: "Personally it has always worried me that I am a 'cheap' peacemaker. Being in Britain talking, writing, demonstrating about peace is in no way taking risks like young servicemen in Iraq. I look for excuses why I should not become involved."

On Saturday, Mr Kember, a self-effacing man who declined social engagements to concentrate on his peace campaigning, paid a grim price for running out of excuses not to witness the suffering of Iraqis for himself.

Two weeks ago the professor, distinguished by his shock of white hair and his six foot-plus frame, left the modest detached house he shares with his wife in a tree-lined avenue in Pinner for the battle-scarred streets of Baghdad. In circumstances that last night remained unclear, he was kidnapped along with two Canadians and an American in a suburb of the city.

Mr Kember, a father-of-two and grandfather who is a leading member of his local Baptist church and was a radiation physicist at Barts Medical College and the University of London, now finds himself at grave risk of becoming a victim of the war he had campaigned so vigorously against.

His group, who were investigating human rights abuses, had reportedly been travelling with "minimal security" when they were seized in the west of the city after dark on Saturday.

The men were in the final days of a two-week fact-finding trip with a Canada-based humanitarian organisation, Christian Peacemaker Teams (PCT). The group, which was working with Iraqi groups and was not involved in missionary work, had been due to return on Friday.

Mr Kember, a man described as "absorbed in his faith", had attended faith conferences in South America and Europe, but this was the first time that Mr Kember had been to Iraq or any war zone.

The absence of any news of the four men's well-being or demands from their captors gave rise to fears that the motive for their abduction may be political rather than financial.

The Foreign Office said that a multinational "hostage crisis" team had been set up in Baghdad to try to secure the release of the men. Jack Straw, the Foreign Secretary, said that the Iraqi authorities had pledged "every assistance" to free the captives.

In a separate incident, two Britons were killed and three injured yesterday when gunmen ambushed a minibus carrying Shia pilgrims to religious sites south of Baghdad. The dead men were named as Saifuddin Makai, 39, from Streatham, south London, and Husain Mohammedali, 50, from Harrow, north-west London.

Yesterday Mr Kember's neighbours in Pinner expressed surprise that he was in Baghdad. One man said: "I was surprised to see him in Iraq at all, let alone in trouble. I knew him as a quiet adventurer, someone who travelled a lot around the world. But guns in Baghdad is something else."

But friends of Mr Kember and his wife, Pat, a retired teacher, who was being comforted by family members last night at an undisclosed location, underlined the retired researcher's devotion to the causes he cherished.

One of the Kembers' daughters, also a teacher, and her husband travelled from their home in Dorset yesterday to be with her mother.

The Rev Alan Betteridge, president of the UK Baptist Peace Fellowship, who has known Mr Kember for more than 40 years, said: "Norman is a very committed worker for non-violence and peacemaking. He is a very gentle man, quiet, with a good sense of humour.

"He does not try to force his views on people - a listener rather than a talker and very committed to what he believes. I hope he has the opportunity to tell his captors about his work."

CPT, a pacifist group based in Toronto which cites the removal of coalition forces from Iraq as one of its aims, declined to comment on the abductions.

Mr Kember was part of a delegation of around eight people who had gone to Iraq to meet local human rights campaigners and assist with the setting up of a Muslim peacemakers' organisation. The organisation had sent four previous civilian delegations to Iraq.