At least 1,300 Christian families have fled the Iraqi city of Mosul after an upsurge of violence against them by Muslim extremists, the authorities say.
Thousands of people have sought refuge in outlying villages since last week after a dozen Christians were murdered, said local official Jawdat Ismail.
Iraqi Prime Minister Nouri Maliki has vowed to protect the community.
About a third of Iraq's estimated 800,000 Christians are believed to have fled abroad since the invasion of 2003.
Mr Ismail, head of Mosul's bureau of displaced people, said food and other aid is being distributed to those who have recently left the city.
More than 8,300 people have fled the violence, blamed on Sunni militants, this month, according to the Associated Press news agency.
In a statement on Tuesday, the US condemned the violence against Iraq's Christians.
"The US embassy in Baghdad condemns the recent attacks against Iraqis in cities such as Baghdad and Nineveh, including those attacks targeting Christian communities in Mosul," it said.
Police have set up checkpoints at churches in Mosul's four largely Christian areas and are patrolling the streets on foot, a correspondent for the AFP news agency has reported.
A major operation by the security forces aimed at displacing insurgents has been under way for months in Mosul, which is considered by US and Iraqi commanders as the last urban stronghold of al-Qaeda in Iraq.
But the BBC's Jim Muir in Baghdad says that, unlike similar campaigns in the Iraqi capital and Basra, the situation in Mosul seems to be getting worse.