The British government concluded Tuesday that Margaret Hassan, a British-Iraqi relief official who worked on behalf of poor Iraqis for more than 20 years, was probably killed by kidnappers who seized her in Baghdad a month ago.

The abduction of Hassan, 59, had provoked outrage among Iraqis. Hassan had remained in the country in support of humanitarian efforts during and after the U.S. invasion, defying risks that led most aid organizations to withdraw from Iraq.

British officials reported Hassan's likely death after studying a videotape provided by al-Jazeera television in which a blindfolded woman was shot in the head at point-blank range. The satellite network, based in Qatar, declined to broadcast the execution.

"As a result of our analysis we have today had to inform Margaret Hassan's family that, sadly, we now believe that she has probably been murdered, although we cannot conclude this with complete certainty," British Foreign Secretary Jack Straw said in a statement released in London late Tuesday.

"To kidnap and kill anyone is inexcusable," Straw said, offering condolences to Hassan's family. "But it is repugnant to commit such a crime against a woman who has spent most of her life working for the good of the people of Iraq."

Although the report of Hassan's death came within days of a fierce battle by U.S. forces to dislodge insurgents in the central Iraqi city of Fallujah, many Iraqis focused on her killing as a meaningless act.

"Did they win? Is it something great for these men to kill an old woman?" said Sawsen Bayati, 35, who heard the news in a Baghdad kebab shop. "They cannot do anything to the American Army -- that's why they go after those innocent people.

"Oh, how I miss safety."

There have been more than 170 kidnappings since April, and at least 34 people have been killed. The killings of hostages have brought widespread condemnation from among Iraqis, who often say such atrocities sully the image of Islam.

Hassan, director of CARE International's operations in Iraq, was a harsh critic of U.N. sanctions against the country before the U.S. invasion that ousted President Saddam Hussein. She helped produce surveys demonstrating that the U.S.-sponsored measures contributed to the deaths of thousands of children.

In various interviews, she distanced her operation from the United States, emphasizing that the CARE programs she ran through the 1990s to bring clean water and health care to Iraq's poor were technically run by the Australian branch of the charity, not its U.S. headquarters. After her abduction, the organization closed its operations in Iraq, joining many other international groups that have said they cannot operate safely in the country.

Hassan, who was born in Dublin and held British as well as Irish citizenship, had lived in Iraq since 1974, moving to Baghdad and becoming an Iraqi citizen after marrying Tahseen Ali Hassan, the son of a prominent family in Basra, in the far south.

She was kidnapped by gunmen Oct. 19 during her morning commute to CARE's office in west Baghdad. "It's a disaster for Iraq," her husband said shortly after the abduction. "Her whole life she worked for the Iraqi people."

Following news of the kidnapping, gritty video footage of the captive showed up on Arab satellite channels. The announcer read a demand that British troops be pulled out of Iraq. A subsequent video showed Hassan breaking down in tears and pleading for her life. Al-Jazeera refused to air a later tape, in which the gaunt captive collapsed on camera and a man doused her with a bucket of water.

There was anger in Iraq over the abduction. Iraqis on crutches and in wheelchairs gathered at a protest in Baghdad. The Association of Muslim Scholars, an organization of Sunni clerics that vocally supports the insurgency, issued a declaration that the aid worker was not a legitimate target.

At first, the protests appeared to have an effect. Her captors passed along word that they did not want to kill Hassan, but were holding her in an effort to embarrass the British government, the Bush administration's most prominent ally in the war.

But there was conflicting information about her status. On Nov. 2, al-Jazeera reported that the kidnappers had threatened to turn Hassan over to the group headed by Abu Musab Zarqawi, a Jordanian extremist who boasted of beheading other foreign hostages. Three days later, a message posted on the Internet by Zarqawi's group criticized her abduction, urging her release.

Al-Jazeera received the latest video at about the same time a woman's mutilated body was found on a street in Fallujah. The body remains unidentified.

Hassan's four brothers and sisters said that her "love of the Arab people started in the 1960s when she worked in Palestinian camps, living with the poorest of the poor and supporting the refugees."

"Our hearts are broken," Hassan's family said in a statement after al-Jazeera reported receiving the video. "We have kept hoping for as long as we could, but we now have to accept that Margaret has probably gone and at last her suffering has ended.

"Nobody can justify this," the statement by Hassan's family concluded. "Margaret was against sanctions and the war. To commit such a crime against anyone is unforgivable."

Special correspondent Naseer Nouri contributed to this report.

Margaret Hassan was seized Oct. 19.