Clashes have erupted in the Iraqi city of Falluja as residents began returning for the first time since a major US and Iraqi offensive there.
Residents ignore warnings about clashes and unexploded mines
The Iraqi government had authorised a group of 2,000 to return to inspect their homes but only about 500 arrived.
Horrified by the destruction they saw, many said they did not intend to stay.
Most of Falluja's Sunni population of about 250,000 fled November's fighting which has left the city in ruins, without running water and electricity.
In other developments in Iraq:
- The US military says three US marines are killed in the volatile al-Anbar province, which includes Falluja
A US general says it appears that a suicide bomber who killed 22 people at a military base in Mosul on Tuesday was wearing an Iraqi military uniform
- More than 40 suspected Iraqi
insurgents are arrested by US marines during a series of raids south of Baghdad
- A policeman is killed in a missile attack on a Baghdad police station
- The police chief in al-Anbar province resigns after an attempt by gunmen to kill him, the province's governor says.
At the US checkpoints, Iraqis of military age were fingerprinted and had their irises scanned to try to ensure that no insurgents returned.
An eyewitness said some of the first citizens to re-enter the city did so in their private cars, after being given badges clearing them to enter their houses in the Andalus neighbourhood.
This is one of 18 districts in the west of the city, which is said to have seen less destruction than other neighbourhoods.
As residents waited in line, there were sporadic clashes with insurgents in many parts of the city including an incident in which US military jets demolished a building from which US forces had come under fire, the US military said.
It was a bad beginning to what may have been intended as a showcase event to bolster confidence in the run up to next month's elections, says the BBC's Jim Muir in Baghdad.
It is hard to see how a mass return can be staged and the city normalised and reconstructed when it is still, apparently, a battleground between the Americans and their enemies who have sworn to defeat them here, he adds.
Many civilians who fled the city to neighbouring areas have said they are desperate to return.
Many have been camping out in winter temperatures in tents, or staying in schools and other public buildings.
National Security Minister Kassim Daoud told reporters: "We have told them that there are areas where the debris has not been removed so far, there are homes that are destroyed, there are mines in some streets, but our people insisted that
they want to return to their city."
US officials acknowledge that returnees will be shocked
The initial group of 2,000 people is part of a staged return that is expected to last a few weeks.
The government says it has set up water tanks for them in the city, and will give each returning resident $100.
It is also promising to pay compensation to the many whose homes have been destroyed or damaged.