Iraq's Prime Minister Nouri has urged residents and tribes in the besieged city of Fallujah to force out al-Qaeda militants.
Nouri al Maliki says if the insurgents aren't expelled, the city will face intense military action within days.
Iraqi forces are preparing to recapture the city, and Mr Maliki said that if the people expelled "terrorists", it would ensure "their areas are not subjected to the danger of armed clashes".
Hundreds of people have already fled Fallujah in the Sunni dominated western province of Anbar. Along with most parts of the provincial capital Ramadi, it was taken over by al-Qaeda fighters last week and Iraqi forces are now preparing to recapture the city after already subjecting it to air strikes and shelling, Radio New Zealand's correspondent in Washington reports.
The Islamic State of Iraq and the Levant wants to take over the whole region - and that is worrying the United States and its allies.
The US and Iran have offered military support, but not troops. However, Washington has said it will speed up the delivery of hardware, including Hellfire missiles and surveillance drones - 10 in the next few weeks and another 48 later in the year.
White House spokesman Jay Carney said it was up to the Iraqis to take the lead, but the US was "working closely with the Iraqis to develop a holistic strategy to isolate the al-Qaeda-affiliated groups".
President Maliki is a Shi'ite and his government has little support in Fallujah. The Sunnis accuse the government of ignoring their needs and marginalising them politically. Iraqi officials accuse the Sunnis of involvement in terrorism.
The latest surge in violence began after government troops broke up a protest camp by Sunni Arabs in Ramadi in December last year.
Fallujah is highly symbolic for Sunni Arabs, who call it the Jerusalem of Iraq.