New footage of hostage Margaret Hassan weeping as she pleads with Britain to save her life has been broadcast on the al-Jazeera TV station.
Margaret Hassan urges British forces to withdraw from Iraq
Mrs Hassan begs Prime Minister Tony Blair to withdraw British forces from Iraq to save her from the same fate as murdered British captive Ken Bigley.
She is shown saying: "Please help
me, please help me, these might be my last hours."
Mrs Hassan, seized on Tuesday, heads Care International operations in Iraq.
Foreign Secretary Jack Straw described the video as "extremely distressing" and said: "I have the greatest sympathy for what her family is
"Margaret Hassan has spent more than 30 years working for the Iraqi people. We hope all Iraqis will join us in calling for her immediate release."
Mrs Hassan, who has dual British and Iraqi nationality and is married to an Iraqi, says: "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 are abducted, and we might die."
The video shows her obviously distressed and putting her head in her hands.
Her plea follows UK Defence Secretary Geoff Hoon's announcement that 500 Black Watch soldiers and 350 support personnel will move from Basra to the US sector in central Iraq.
No responsibility claimed
Downing Street has declined to respond to Mrs Hassan's call for British troops to stay out of Baghdad and quit Iraq.
An editor at al-Jazeera said the network had received the tape on Friday but refused to give details of how or where.
He said the tape contained only Mrs Hassan's statement and did not include any claim of responsibility or clue to the identity of her kidnappers.
Mrs Hassan's husband has pleaded on television for her release
Mrs Hassan, who has lived in Iraq for 30 years, was kidnapped at about 0730 (0430 GMT) on Tuesday on her way to work in Baghdad.
Care International has suspended its aid operations in Iraq following her abduction.
Numerous appeals have been made from within Iraq for Mrs Hassan, who was born in Dublin, to be freed unharmed.
Interviews with her Iraqi husband Tahseen Ali Hassan have been shown at length on the two most watched stations, al-Jazeera and al-Arabiya.
He said: "I don't know who has kidnapped her but they should know that my wife has worked almost all her life for the Iraqi people and considers herself an Iraqi."
Both stations also broadcast interviews with her fellow aid workers, stressing her many years of humanitarian work in Iraq.
An appeal from the Irish Prime Minister, Bertie Ahern, has been shown repeatedly and similar calls from the Iraqi interim government widely reported.
Ken Bigley and two US colleagues were abducted from their Baghdad home by the Tawhid and Jihad group on 16 September.
The beheading of Mr Bigley, a 62-year-old engineer from Liverpool, was shown on video on 8 October.