"The city's main hospital received six injured," Salih al-Issawi, a doctor in Fallujah General Hospital told Xinhua. US warplanes heavily pounded the eastern parts of the city, where three houses were damaged, including one totally destroyed, witnesses said.

They said that US warplanes and artillery pounded the industry area, adding the forces also blocked the highway linking Fallujah with Baghdad.

On the other hand, insurgents responded with fierce mortar and rocket-propelled grenade attacks against US positions on the edge of the city.

The US military said in a statement that US warplanes launched five airstrikes against suspected insurgent positions in the city, beginning at 4:40 p.m. (1340 GMT) Thursday and ending at 1:10 a.m.Friday (2210 GMT Thursday).

"Iraqi security forces and the 1st Marine Expeditionary Force continue to degrade and disrupt anti-Iraqi (insurgent) forces in the Fallujah-Ramadi area," a military statement said. Fallujah, 50 km west of Baghdad, remains the top security concern for US and Iraqi officials and is on the list of cities to be retaken from insurgents by launching an all-out offensive as part of a campaign to restore peace in Iraq for elections due in January.