The US forces on Monday launched two air strikes and ground fire on Iraq's flashpoint city of Baquba after clashes between insurgents and the Iraqi security forces, killing some 20, reports reaching here from Baquba said.

The new wave of violence burst out when insurgents attacked the US soldiers and Iraqi police in Baquba, which prompted the US forces to drop two 500-pound bombs on suspected insurgent targets in the southern outskirts of the city, confirmed US military spokesman Captain Bill Coppernoll.

Some 20 insurgents were killed and four US troops injured, added the spokesman.

Coppernoll said insurgents in the city on Monday morning attacked the 1st Infantry Division soldiers and a police station with rocket-propelled grenades and small arms fire.

Witnesses said turmoil sprawled across Baquba, some 55 km northeast of Baghdad, as the US and Iraqi forces battled hard against the armed insurgents in a bid to restore order.

On Sunday, hundreds of marchers took to the streets in Baquba, protesting against the US-Iraqi troops attack on Falljah and denouncing Iraq's interim Prime Minister Ayad Allawi for ordering the operation.

The over week-long major assault launched by the US-Iraqi forces on the restive Fallujah has killed some 1,200 insurgents with nearly 500 others arrested as Allawi gave a final green light to the deadly offensive.