Christians were fleeing Iraq's jihadist-held city of Mosul en masse after mosques relayed an ultimatum giving them a few hours to leave.
Messages telling Christians to leave the city by today were blared through loudspeakers from the city's mosques yesterday.
The Islamist State jihadist group took over the city last month.
A statement was issued saying Mosul's Christians should convert, pay a special tax, leave or face death.
One of most Iraq's senior Christian clerics said that homes were being tagged with the letter N for "Nassarah" a term used in the Koran to refer to Christians.
The statement, which was seen by AFP news agency said: "there will be nothing for them but the sword" if Christians reject those conditions.