Kenneth Bigley's elderly mother was taken to hospital last night after she had made a tearful television plea for her son's life.

Elizabeth Bigley, 86, told the terrorists that he was "only a working man who wants to support his family".

In Washington, President Bush said that the kidnappers were "trying to shake our will... but I’m not going to yield".

At his side was, Iyad Allawi, the Iraqi prime minister, who added: "When governments negotiate with terrorists, everyone in the free world suffers. When political leaders sound the siren of defeatism in the face of terrorism, it only encourages more violence."

Just before Bigley's plea, Tony Blair telephoned the family for the second time this week.

Paul Bigley, the kidnapped Briton's other brother, slammed the US government.

"Blair and Jack Straw are Bush's puppets at this moment," he said.

"They are waffling on about not negotiating. If Bush wasn't pulling the strings I am damn sure they would be behind the release of some prisoners to save my brother’s life."

Blair has remained publicly silent this week for fear of provoking the captors but the Indepedent reports he is planning on making a robust defence of his refusal to negotiate with terrorists at the Labour Party conference.