Three Italian troops and a Romanian soldier have died after their vehicle was hit by a roadside bomb in southern Iraq, Italy's defence ministry says.
Bogdan Hancu was taking part in a patrolling and monitoring mission
The Romanian, Bogdan Hancu, 28, is the first Romanian soldier to be killed in action in Iraq.
The attack happened in the city of Nasiriya where the Italian contingent of 2,500 troops is based.
In January, the Italian government announced it would pull its troops out of Iraq by the end of the year.
A fourth Italian travelling in the vehicle was seriously injured, officials said.
Newly elected Prime Minister Romano Prodi described the attack as a tragedy that "affects all of Italy".
He also said that Italy's planned withdrawal of Italian troops from Iraq would continue.
An Iraqi militant group claimed that it was responsible for the deaths of the four soldiers.
"The Islamic Army in Iraq was able to destroy a vehicle belonging to the coalition forces... killing three Italian soldiers and one Romanian," the group said in a statement posted on the internet.
The Romanian foreign affairs ministry condemned "the terrorist attack in Nasiriya" and expressed its condolences to the family of the Romanian soldier.
It said that Romanian troops were in Iraq "to help provide security, which is needed to allow the development of Iraq's political process and the return of Iraq to normalcy," AP news agency reported.
The mother of Bogdan Hancu told the BBC that nothing was worth the life of her son, even if he became a national hero.
Maria Carmen Hancu said that Romania has no business being militarily involved in Iraq.
"Humanitarian missions, yes, we could build bridges, roads, schools. We should withdraw our troops and this isn't linked to my son's death. We have no business being there, our children are dying needlessly".
Italy, a staunch ally of the US administration under outgoing PM Silvio Berlusconi, sent about 3,000 soldiers to Iraq to help with the reconstruction in the south after the fall of Saddam Hussein in 2003.
But the involvement in the war has been deeply unpopular at home and was a key issue in the hotly contested Italian election earlier this month.
The force has suffered several attacks, the worst being in November 2003 when 19 Italians, mostly police officers, were killed in a suicide attack in Nasiriya.
Italy currently has some 2,600 troops in Iraq and Romania has 860 soldiers there.