Captors threaten Hassan handover

Mrs Hassan's sisters made an emotional plea to her captors

Gunmen holding hostage Margaret Hassan said they would hand her to militant Abu Musab al-Zarqawi if British troops do not leave Iraq within 48 hours.

The warning was made by a hooded figure on a video broadcast on the Arabic TV station Al-Jazeera.

Jordanian-born Zarqawi has admitted beheading several foreigners, including Briton Ken Bigley.

The video has not been aired in full, but is said to show Mrs Hassan pleading for her life before suddenly fainting.

Al-Jazeera said it could not play the whole tape for humanitarian reasons.

Irish prime minister Bertie Ahern said the content of the tape was "distressing".

Mr Ahern also said there were "a number of very dangerous and very serious timescales stated".

Margaret Hassan has already been shown on video released by her captors

He was speaking after he and Mrs Hassan's Irish relatives pleaded for the Care International aid worker's release.

Iraq links

Mrs Hassan's sister Deirdre spoke publicly for the first time of her anguish for the 59-year-old and stressed her Irish roots and strong Iraq links.

Fighting back tears, she said: "We have listened to your demands and begged Tony Blair and the British Government to release the women prisoners and also not to move the troops.

"But we are Irish and have no influence on the British Government".

Speaking on behalf of her family, Mrs Fitzsimons said her sister was an Iraqi and had dedicated her life to helping the Iraqi people.

Our sister is a friend of Iraq and we beg you to please let her to go home to her husband who loves her. Please don't hurt her Deirdre Fitzsimons

"Our sister is a friend of Iraq and we beg you to please let her to go home to her husband who loves her. Please don't hurt her."

Mr Ahern also made his second appeal for the aid worker's release.

He said Mrs Hassan had no political associations and represented no one but the vulnerable and the poor.

"Your quarrel is not with Margaret Hassan, nor is it with the Irish people who have been a firm friend of the Arab nation," he said.

Direct kidnapping

Mrs Hassan was snatched by gunmen two weeks ago. She has since been shown on videotapes pleading for Britain to withdraw troops from Iraq.

Zarqawi's Tawhid and Jihad group, believed to number up to 500 militants, is suspected of the direct kidnapping and beheading of a number of Westerners in Iraq, including Mr Bigley last month.

Many of the killings have been videotaped and broadcast over the internet.

Mrs Hassan, 59, was born in Dublin and has family in Kenmare, County Kerry although her sisters Deirdre and Catherine Fitzsimons now live in London.

Mrs Hassan, who has British, Irish and Iraqi nationality, was seized on 19 October by unidentified kidnappers.

A Foreign office spokesman would not comment on the latest events, saying the government's position of not negotiating with kidnappers had been made clear.