Kidnapped Irish-born hostage Ms Margaret Hassan has appeared in a video on Arab television pleading for her life.
"This might be my last hour. Please help me. The British people, tell Mr Blair to take the troops out of Iraq and not bring them here to Baghdad. That's why people like myself and Mr Bigley have been caught. Please, please, I beg of you," a distraught Ms Hassan, who is in her 60s, said on the video broadcast on Al-Jazeera.
Mr Bigley was beheaded by his captors earlier this month.
The video did not show Ms Hassan's captors, nor were they identified. An editor at Al-Jazeera said the network received the tape today but refused to say how or where. He said the tape included only Ms Hassan's statement.
Ms Hassan, head of the charity CARE International, was born in Dublin and holds Irish, British, and Iraqi citizenship. She has lived in Iraq for more than 30 years.
She was seized by gunmen on Tuesday on her way to work in western Baghdad.
Her husband said earlier today he was awaiting contact from her kidnappers. Mr Tahseen Ali Hassan said he had not sought information from or spoken to any Irish officials or other foreign diplomats.
Speaking on RTÉ radio this morning, he said he could see no reason - political or religious - why his wife was abducted. "She is doing things for Iraq and has nothing to do with politics," he said.
Mr Hassan said once he hears from the group responsible, he will act accordingly. He thanked Ireland for its support and said he appreciated the Government's intervention, saying he believed the fact his wife was born in Ireland and has Irish parents could help secure her release.
Tonight the Taoiseach issued in a statement calling for the immediate release of Ms Hassan.
The statement said: "The people of Ireland have been shocked by the kidnapping of Margaret Hassan. Margaret is a woman who has lived in Iraq for thirty-two years. She is a person who has selflessly worked for the benefit of her Iraqi fellow citizens and fought for the rights of the Iraqi poeple for many years.
"Taking Margaret from her family is a cruel and shocking act. To harm her in any way would be unthinkable. I call on her captors, on behalf of the Government and people of Ireland, to release her immediately." Yesterday, the Minister for Foreign Affais and his Palestinian counterpart, Dr Nabil Shaath, appealed to the kidnappers on Arabic TV station Al-Jazeera for Ms Hassan's release. The appeals were broadcast repeatedly throughout the day.