The US military has said eight Iraqis have been killed in a mortar attack on a market in a town northeast of Baghdad. It is understood those killed were civilians.
A US military spokesman said it was not known who carried out the attack. It is reported 18 people were injured in the incident.
Meanwhile, the US government has said it intends to set a six-month deadline for the writing of a new constitution for Iraq.
In an interview with the New York Times newspaper, Secretary of State Colin Powell said it would be a difficult target to meet.
The new constitution would spell out whether Iraq should be governed by a presidential or a parliamentary system and clear the way for elections and the installation of a new government in 2004.
Mr Powell said the US would not transfer power to Iraq until then.
US administrators in Iraq have said they are disappointed that the United Nations is withdrawing more staff from the country because of security concerns.
The UN headquarters in Baghdad has been attacked twice in the past six weeks. But US officials said the latest withdrawal was a setback for the post-war reconstruction effort.
Hoshiyar Zebari, Foreign Minister on the US-appointed Iraqi Governing Council, has met UN Secretary-General Kofi Annan to urge him to maintain a strong presence in Iraq.
