British officials in Baghdad are trying to find out if the mutilated body of a woman found in Falluja on Sunday is that of aid worker Margaret Hassan.
Mrs Hassan had lived in Iraq for 30 years and married an Iraqi
The body is reported to have been flown out of Iraq to undergo DNA tests, the BBC's Caroline Hawley in Baghdad said.
Mrs Hassan, who had lived and worked in Iraq for 30 years, was seized by an unknown group in Baghdad a month ago.
On Tuesday, her family said they believed she was dead after a video emerged showing a woman being shot.
Australian Prime Minister John Howard has said he believes the body found in Falluja is that of Mrs Hassan, who worked for an Australian charity.
Mr Howard said: "I regret to have to say... that every indication now is that Margaret Hassan has been murdered by some terrorist in Iraq.
"Her family and the British and Irish governments have concluded that she is dead.
"The body found in Falluja appears to have been Margaret's and the video of the execution of a Western woman appears on all the available information to have been genuine."
On Wednesday, mourners gathered for a service in Mrs Hassan's mother's home town of Kenmare, County Kerry, in the Irish Republic, where her sister and family still live.
Arabic TV news channel Al-Jazeera said on Tuesday it had had a copy of the videotape showing Mrs Hassan's apparent killing for several days, but had chosen not to broadcast it.
The video showing a blindfolded woman being shot in the head has been checked by experts.
Mrs Hassan was driving to her job as director of Care International's Iraq operations on 19 October when she was seized. The agency has since halted work in the country.
If Mrs Hassan's death is confirmed she will be the first foreign female hostage to have been murdered in Iraq.
The only other western woman to known to be currently held in Iraq is Teresa Borcz Khalifa, 54, a Polish-born long-time resident of Iraq who was seized last month.