One marine was killed and three wounded when they came under fire in north east Baghdad while three others were wounded in a separate clash in the city's eastern suburbs, Lieutenant Colonel Pete Owen said.

The first firefight was quelled after Iraqi soldiers opened fire with rifles from multi-storey buildings while the second, involving a battalion, is ongoing, said Owen, executive officer of Regimental Combat Team 1 with the 1st Marine Expeditionary Force.

Extra US troops were being brought in, Owen said, and although the fighting was expected to ease overnight, US marines would push forward at first light Wednesday.

Owen said the Iraqi forces were a combination of paramilitary troops and regulars, and were armed with light automatic weapons and rocket-propelled grenades.

"We're stumbling across little pockets" of resistance, he said, then added with regard to searching Baghdad: "I wouldn't say every house but every block."

Translators were brought in to help evacuate a heavy population of civilians in the capital's northeastern suburbs before the firefight was quelled, Owen said.

US marines had earlier completed their advance to Baghdad, hours after being caught up in a traffic jam as thousands of armoured vehicles and Humvees poured into the capital for a showdown with Saddam Hussein's troops.

The convoy inched its way into the city, crossing the Diyala river, a tributary of the Tigris, at several points where one main bridge had been blown out.

A small suburb at the side of the bridge had been completely destroyed by a firefight and along the river, marines could be seen crossing at makeshift pontoons and bridges dotted along its banks.

As they crossed, some 100 Iraqi civilians were seen fleeing the capital by swimming across the water.

SPACE.WIRE