The gunmen fired 40 to 60 shots from across the Tigris river, with one standing on the roof of a three-storey building and another nearby from inside the presidential compound, said marine Staff Sergeant Chris Thompson.

The marines, located on the other bank of the Tigris near the Palestine Hotel, which houses a number of US officers and most of the foreign media, responded for up to 10 minutes with their machine guns and grenade launchers, he said.

It was unclear what happened to the gunmen. No US casualties were reported.

US marines took cover behind their armored vehicles during the firefight, as cameramen and photographers rushed to take pictures.

The sprawling Republican Palace was bombed relentlessly after the United States and Britain launched the war March 20. The compound was raided by US troops on Monday, two days before Saddam's authority crumbled throughout Baghdad.

SPACE.WIRE