John Reid, the Defence Secretary, said the fate of Mr Kember, 74, was still unknown after his captors set a Saturday deadline for Iraqi prisoners to be freed and troops removed from Iraq.

“We are doing through the Foreign Office, through Jack Straw, everything possible to try and make sure his life is saved and that of his colleagues is protected,” Mr Reid said yesterday. “But we have no further indication of any movement.”

The previously unknown group, the Swords of Righteousness Brigade, claimed responsibility for the capture of Mr Kember after he was seized last month with two Canadians, James Loney, 41, and Harmeet Singh Sooden, 32; and Tom Fox, 54, an American.

All were members of the Christian Peacemaker Teams, a peace group that was one of the last humanitarian groups to have Westerners working in Iraq without armed protection.

Eight foreigners have been abducted in Iraq since November and six are still being held, including a German woman and a French contractor.

On Saturday police found the body of an Egyptian translator who worked for the US military in Saddam Hussein’s home town of Tikrit. An Iraqi Islamist group said it had killed a US security contractor, a claim which has yet to be confirmed.

The Rev Alan Betteridge, a friend of Mr Kember for 20 years, said yesterday that he remained cautiously hopeful that the hostages would be released.

“I’m hopeful because we’re not hearing anything at the moment,” he said. “I feel hopeful, but because of the history of what’s happened in Iraq in the past couple of years I know the possibility of death is there.

“I know how volatile it is and he knew that before he went there. He’s not a foolhardy man. He knew the risks and his wife knew the risks.”

Mr Betteridge, a retired minister, said members of his congregation at the Queens Road Baptist Church in Coventry prayed for Mr Kember during the service as they marked the United Nations Human Rights Day. He added that the efforts of Muslim groups to secure Mr Kember’s release was also encouraging.

The latest appeals were made by Hizb ut-Tahrir, an extremist organisation which Tony Blair has threatened to ban, and Abu Rideh, a Jordanian-born terrorist suspect whose plea was broadcast on al-Jazeera and al-Arabiyah television channels on Saturday.

Last week Abu Qatada, one of Britain’s most high-profile terrorist suspects, made a televised appeal for the men’s release from his maximum- security prison cell.

Mr Kember’s friends said they believed his faith would sustain him, but added that he was also strong physically and mentally.

“I know his strength,” said Mr Betteridge. “Although he is 74, he’s a good advert for being 74. He’s mentally robust, and spiritually, of course; he’s been a Christian for decades and he’s quite sure about his motivation.”

Bruce Kent, the vice-president of CND, said: “Norman is a man of great faith and great determination and deeply Christian and physically quite strong.

“He’s not a depressive. He has a very lively sense of humour. He’s not an egotist. He’s completely self-effacing. In so far as anybody could survive this ghastly thing he will bear up and he will be an encouragement to the other three.”

Mr Kent said he had spoken to Mr Kember’s wife, Pat, 72, on Saturday and that the family was coping well under the circumstances.

“She is behaving incredibly well, strong and calm and faithful,” he said.

“Having been shot into this incredible whirlpool, she’s done wonders and indeed the family has. They’ve had such a terrible trauma and they’ve really pulled together.”

A member of Harrow Baptist Church, to which the Kembers belong, said that the congregation was desperately waiting to hear news from Iraq.

The man, who declined to give his name, said: “We are all rather emotional at the moment.”

Explore UK News

• Crime News

• Education News

• Health News

• Science News

• Scotland News

Times Recommends

• One case exposes grim reality for thousands
• A glass case: Prince who yearns for action
• Elizabeth Gaskell: I won’t see out the year