In Iraq, an armed brigade calling itself the Fallujah Military Council has threatened to punish tribesmen who back government troops.

The warning came hours after Iraq’s prime minister urged people in the besieged city to expel militants to avoid an all-out assault by the army.

Some armed tribesmen from Iraq’s once dominant Sunni minority have been fighting al Qaeda linked militants in the area since last week. But others baulk at taking sides with the Shi’ite government.

In a statement on state television, Prime Minister Nuri al-Maliki promised the army, stationed outside the city, would not attack residential areas as his forces prepare an offensive.

Militants have also seized other key towns in the desert leading to the Syrian border as sectarian conflict expands into a broader regional confrontation.

When Iraqi police broke up a Sunni protest last week in Ramadi, the Anbar capital, deadly clashes fanned tensions across the province that was the heart of the insurgency after the 2003 U.S. invasion that brought Shi’ite majority rule.