The apparent slaying of CARE head Margaret Hassan (search) by her kidnappers deepened the chill among aid agencies already fearful of operating in Iraq.

In Ireland, where Hassan was born, hundreds of mourners packed a church Wednesday to pay final respects.

Political leaders and relatives expressed shock and anger over the fate of Hassan, who was renowned for her 30 years of work in Iraq, distributing medicine, food and supplies to Iraqis suffering under the sanctions of the 1990s.

British officials say they believe Hassan was a blindfolded woman seen being shot in the head by a hooded militant on a video obtained but not aired by the Arab television station Al-Jazeera. She would be the first foreign woman to die in the wave of kidnappings in Iraq. No group has claimed responsibility.

The 59-year-old Hassan, director of CARE International (search) in Iraq, was abducted in Baghdad on Oct. 16.

British and Irish leaders condemned the apparent killing and the European Union said it would make relief efforts in Iraq almost impossible.

Christian Berthiaume of the World Food Program (search), one of many relief organizations that have drastically scaled back operations in Iraq because of security concerns, said Hassan's death would make matters worse.

"That's really a shock," Berthiaume said. "It's a very dangerous place to work, unfortunately, for relief workers."

"If it's true, this is outrageous," said Astrid van Genderen Stort, spokeswoman for the U.N. High Commissioner for Refugees (search) in Amman. She said Hassan "worked even under the most difficult times in Iraq for the good of the Iraqi people, for 30 years."

WFP and other U.N. agencies pulled their international staff out of Iraq after a deadly bomb attack on United Nations offices in Baghdad last year. Many other groups have done the same, leaving local employees in place to carry on work.

CARE said it was in mourning for Hassan. The group has closed its Iraq operations since she was abducted Oct. 19 in Baghdad while she was being driven to work.

In the southwest Ireland village of Kenmare, where Hassan's sister Geraldine Riney lives, hundreds turned out to mourn Hassan at a joint Catholic-Protestant service.

The Rev. Tom Crean, the Catholic parish priest of Kenmare, told mourners — among them more than 100 children in their Kenmare school uniforms — that her killing represented "an unspeakable loss."

Hassan's four brothers and sisters said Tuesday that they believe she is dead.

"Our hearts are broken," they said in a statement. "Those who are guilty of this atrocious act, and those who support them, have no excuses."

A British, Iraqi and Irish citizen, Hassan had lived in Iraq for 32 years and was married to an Iraqi engineer, Tahseen Ali Hassan. She served as CARE director there since 1991.

On Sunday, Marines found the mutilated body of what they believe was a Western woman on a street in Fallujah during the U.S. assault on the insurgent stronghold. The body, clothed in what appeared to be a purple, velour dress, was wrapped in a blanket, with a blood-soaked black cloth nearby. As of Tuesday night, the U.S. command said the body had not been identified.

Hassan's captors had issued several videotapes of her pleading for her life and asking for Britain to withdraw its troops from Iraq and for female Iraqi prisoners to be freed. Ireland, which has been critical of the U.S.-British invasion of Iraq, issued several high-profile appeals for her freedom.

Irish President Mary McAleese said she was "greatly saddened."

"Margaret was remarkable in her love for and devotion to the Iraqi people," McAleese said. "It is a cruel irony that Margaret's captors did not show her the same humanity and kindness which she demonstrated daily to those around her."

Irish Prime Minister Bertie Ahern (search) said "those responsible for abducting Margaret stand condemned by everyone throughout the entire international community."

British Prime Minister Tony Blair said he shares the family's "abhorrence at the cruel treatment of someone who devoted so many years of their life to helping the people of Iraq."

Hassan was the most prominent of more than 170 foreigners kidnapped in Iraq this year. At least 34 have been killed. Besides Hassan, eight foreign women have been abducted. Seven have been released.

Teresa Borcz Khalifa (search), 54, a Polish-born longtime resident of Iraq who was seized last month, is now the only one whose fate remains unknown.