American warplanes on Tuesday night pounded Fallujah, Iraq, where US Marines have engaged in a two-week standoff with insurgents.

Two AC-130 gunships began bombing two suspected insurgent positions shortly before 10:30 pm, CNN quoted Marines and Pentagon officials as saying.

The shelling appeared to have set off at least two large secondary explosions, the broadcaster said.

The AC-130s fired 105 mm cannon while circling the area, Marines told CNN.

Several mosques broadcast verses from the Quran during and after the bombing.

Fallujah has been the site of fierce resistance to the US-led occupation of Iraq.

Pentagon officials said the strikes were in response to a threat to Marines there.

"Marines responded by directing precision weaponry against the enemy forces in order to defend themselves," a military statement said.

Earlier on Tuesday, a coalition military spokesman said 64 insurgents were killed in fighting with US-led forces near Najaf.

Seven died during fighting after a US patrol was attacked, and a further 57 were killed in a heavy battle during which US aircraft destroyed an anti-aircraft gun, the coalition said.

"There was something like 57 enemy killed in that vicinity," Brig Gen Mark Kimmitt was quoted as saying.