The U.S. military said two air raids after midnight destroyed "known anti-Iraqi barricaded fighting positions" in the northeast and southeast of the Sunni Muslim city, about 30 miles west of Baghdad.

The military uses the term anti-Iraqi forces to refer to Iraqi insurgents and foreign Islamic militants led by al Qaeda ally Abu Musab al-Zarqawi who it says are entrenched in Falluja.

There was no immediate information on whether there had been any casualties from the attacks.

Falluja residents said U.S. ground troops had apparently stayed on the perimeter of the city.

The strikes followed what witnesses said was an intense late-night bombardment on Wednesday of eastern and northwestern districts by AC-130 aircraft and tanks that shook the city for half an hour.

The bombardment was the heaviest inflicted on Falluja for several weeks, the witnesses said.

The U.S. military is poised for an assault on Falluja and another Sunni city Ramadi, also west of Baghdad, as part of a drive to pacify Iraq (news - web sites) before national elections planned for January.

On Wednesday, U.S. air strikes sent up plumes of black smoke from the eastern edge of Falluja. A woman was badly wounded and a teenage girl lost her right leg in the raids, hospital official Issam Mohammed said.

Iraq's U.S.-backed interim government has vowed to retake all rebel strongholds before the elections. It has not publicly given the go-ahead for the storming of Falluja and Ramadi.

Interim Prime Minister Iyad Allawi is visiting Europe.

Most of Falluja's 300,000 people have already fled the city, where they say U.S. bombardments cause civilian casualties and fuel already fierce anti-American sentiment.