Warplanes pounded northeastern Fallujah, the backbone of the rebellion in Al-Anbar, sending columns of black smoke into the sky, said an AFP correspondent embedded with the marines.

The strikes followed fighting that has killed eight marines and at least 17 suspected rebels in Al-Anbar since Friday, the US military said, without specifying whether the marines' deaths occurred in Fallujah itself.

Seven marines assigned to the Ist Marine Expeditionary Force were killed in two separate operations Sunday, the marines said in a statement which gave no further details. Another marine was killed Saturday.

The fighting erupted in Fallujah after days of relative calm following last month's blistering assault on the Sunni Muslim city by US and Iraqi troops.

Coalition troops killed hundreds of fighters during the attack, which began November 8, but have continued to face resistance, often in parts of the city they had previously cleared.

"They hole themselves up in houses and they wait for the chance to kill an American," said Lieutenant Rex McIntosh.

Many of those fighters still hiding in Fallujah's ruined neighborhoods had escaped previous sweeps by the marines, he added.

"There's a fairly effective cordon around the city but not every unit has been doing a full clearing," he said, as his unit searched house-to-house for rebels or weapons caches Sunday.

Marines from the battalion found themselves in a running battle with insurgents that raged on Friday and Saturday.

"We had very, very heavy contact against a group... which was bypassed in previous sweeping operations," McIntosh said. "By the end of Saturday afternoon we counted 17 dead rebels."

It was unknown who the dead fighters were but many of them appeared to be foreigners, he said.

"Sometimes we find a pile of passports in a cache or a house, but the identification process is often difficult due to the condition of the bodies."

The fighting marked an escalation in violence after days of relative calm, forcing the marines to call in both tanks and fighter jets.

Clashes erupted again Sunday as marines battled fighters in northeast Fallujah, according to one marine, who told AFP the area was supposed to have been cleared of insurgents.

Large explosions could be heard and flashes lit the sky Sunday night as jets roared overhead, the correspondent said.

Marines had earlier told AFP that rebels were creeping back into previously cleared city blocks, and the military was in a race to seize weapons caches before they could be used against them.

"They are just like rats, no matter the amount of poison you spread around, they keep on coming back into the house," said one marine.

Large numbers of weapons, mostly assault rifles and mortars, continue to be found in abandoned homes. At least 70 rifles and other weapons, including rockets and grenades, were seized by marines patrolling the city on Sunday.

As US and Iraqi forces try to restore order in the devastated city, hundreds of thousands of residents driven out by the fighting wait to return to their homes.

The marine's top commander in Iraq, Lieutenant General John Sattler, said last week he was told by Iraqi military officials that civilians might be allowed back into Fallujah at the end of December.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.