Two Britons were killed and three injured when a gunman attacked a bus carrying Muslim pilgrims south of Baghdad.
Gunmen attacked the bus carrying Shiite Muslim pilgrims to religious sites south of the capital when it neared a checkpoint in the Dora neighbourhood, according to Iraqi police.
The dead and injured - four men and one woman, apparently of South Asian heritage and carrying UK passports - were taken to Baghdad's Yarmouk hospital, an official said.
A Foreign Office spokesman said: "Our consular and security staff are investigating the reports.
"They have heard it could be two British nationals, but at this stage we know no more than that.
"The reports are being investigated."
The news of the deaths comes after the kidnapping of British aid worker Norman Kember, of Pinner, north west London, who was snatched alongside two Canadians and an American on Saturday.
Mr Kember, a retired professor, was reportedly taken from a potentially dangerous district of western Baghdad along with the three other members of the group.
It is believed the group could have been in the area with "pretty minimal" security.
Mr Kember's wife Pat said last night she was receiving a great deal of support.
Mr Kember, believed to be in his 70s, used to be secretary of a Baptist peace group in Pinner, but Mrs Kember said he was no longer representing them.
"He is representing a number of different organisations," she said. "People are being very, very good to me and I'm being supported."
Mrs Kember added that she had been told not to speak to the media and that police officers were on their way to speak to her about the kidnapping.
The Foreign Office would not confirm who Mr Kember was working for or the location where he was kidnapped.
A spokeswoman said: "We can confirm his name but we cannot give any more details at this stage.
"We will be in touch with the Iraqi authorities, and with the other countries involved, the Americans and the Canadians.
"We will be setting in motion an urgent investigation."
An official at one of the peace groups where Mr Kember sometimes works described him as a friendly, resourceful man.
He was shocked at the news that he had been kidnapped, saying he was unaware he was even in Iraq. As far as he knew, this was Mr Kember's first visit to the country.
The official said Mr Kember was "very much involved" in campaigning for peace.
"He is a friendly and affable person and very committed to what he believes - a man of a great deal of resource," the official said.
He added that Mr Kember was in his 60s or 70s and had "lovely white hair".
He said: "He was incredibly active. He was against the war. He went on the big demonstration against it in London and felt very strongly about it.
"As far as I know, he went to Iraq as an individual, he didn't go as part of our group."
A spokesman for the RNLI, which employs Mr Kember's son-in-law, said today they were offering any support they can to the family.
Ian Thomas works as a lifeboat helmsman in Weymouth, Dorset, where he lives in Trinity Terrace with his wife, Jo.
Mr Kember's daughter is a teacher at St Mary's Church of England Middle School in Puddletown.
Their son Benjamin, Mr Kember's grandchild, was christened on board a lifeboat two years ago.
The RNLI spokesman said that it was "obviously a distressing time" for the family.
He added: "The thoughts of all at the RNLI are obviously with Ian and his family at this difficult time.
"The lifeboat station staff and management and crew are doing what they can to support him."
St Mary's School declined to comment this morning.
Up to 200 foreigners have been abducted in Iraq over the past year and a half.
Two British civilians were taken hostage and killed.
Aid worker Margaret Hassan, who was head of Care International in Iraq and had lived in the country for 30 years, was kidnapped in October last year. Her body has never been found, but she is believed to have been murdered.
Kenneth Bigley, a 62-year-old engineer, was kidnapped in September last year and beheaded, with his death captured on video.