A video showing Mr Bigley alive was broadcast four days ago

Mr Bigley, whose mother is from Ireland, was taken hostage with two Americans, who have since been killed.

Ireland's Minister for Foreign Affairs Dermot Ahern said "there are many people in Ireland who are worried about this situation".

Mr Bigley, held for 18 days, was seen alive in a video shown four days ago.

"I have made contact with Iranian diplomats in Ireland and with the Jordanian government," Mr Ahern said.

"I raised it with my officials on my first day in the department. Any pressure we can put on to be of assistance to the British Government, we will use."

I don't think they want to murder him but they want something out of it politically Daud Abdullah

It is not the first move by Irish politicians to hasten Mr Bigley's release.

The Taoiseach Bertie Ahern, Sinn Fein president Gerry Adams and the Irish Labour party's Michael D Higgins have all had pleas broadcast on Arab television station Al-Jazeera.

SDLP MP and Nobel Peace Prize laureate John Hume also made a direct appeal for his release after being approached by the Bigley family.

Meanwhile, a Muslim negotiator involved in trying to free Mr Bigley has expressed guarded optimism he will be freed, the Independent on Sunday reported.

Daud Abdullah, who visited Baghdad last week, said he believes the 62-year-old Briton is still alive and will be released.

Mr Abdullah, who led the delegation from the Muslim Council of Britain (MCB) to Baghdad, said "I feel he will" survive, the paper reported.

"If they had wanted to kill him, they would have done so. I don't think they want to murder him but they want something out of it politically - apart from humiliating Tony Blair and the government."

Pamphlet appeal

Two American colleagues taken hostage with Mr Bigley on 16 September have since been beheaded.

On Saturday new appeals from the council were published in two Baghdad newspapers, a day after another 100,000 leaflets appealing directly to the kidnappers were distributed around the capital.

It was the second time such leaflets have been distributed in the city, with 50,000 being handed out by the British Embassy last week.

British Muslim leaders also appealed to Mr Bigley's captors in the pamphlet, saying the kidnap was not consistent with the Islamic faith.