Three British soldiers from the Black Watch regiment were killed in a suicide car bomb attack south of Baghdad.
A translator also died and eight British soldiers were wounded in the checkpoint blast and subsequent mortar fire according to the UK government.
Earlier, at least four Iraqis were killed and 18 injured in a car bombing outside a city council building in the town of Dujail, north of Baghdad.
US aircraft continued to attack the city of Fallujah as locals braced for a full military assault after the re-election of US President George W Bush.
Meanwhile, the Iraqi Prime Minister, Iyad Allawi, has called on other countries to get off the fence and get involved in stabilising Iraq.
Speaking after discussions with Italy's Prime Minister Silvio Berlusconi during a visit to Rome, the interim Iraqi leader said the situation in Iraq could not be resolved 'without the help of all the important countries'.
Separately, the international aid group, Médecins Sans Frontières, has announced it is halting activities in Iraq because of what it called the 'extreme risks' run by aid workers in the country.
The group, which has around 90 staff members in the country, mostly Iraqis, said the warring parties had repeatedly shown their disrespect for independent humanitarian assistance.
The announcement comes as gunmen continue to hold hostage the Irish aid worker, Margaret Hassan, in Iraq.
