Amid wrecked jets and hangars, the greatest prize

American forces moved into positions on the eastern and western edges of Baghdad yesterday, in anticipation of either a siege or a final assault on the centre of Saddam Hussein's power.

In the early hours of this morning they pounded eastern Baghdad with an intense artillery barrage, lighting up the sky with explosions and drawing return fire from Iraqi defenders. The battle appeared to be taking place about 20 miles east of the city centre.

Last night military spokesmen said soldiers of the 101st Airborne Division and the 94th Battalion were reinforcing the 3rd Infantry Division, which spearheaded the assault on Baghdad airport. Troops from the 101st will help to secure the airport, 12 miles south-west of the city centre and the biggest prize in the 16-day-old war. Members of the 94th Engineer Combat Battalion (Heavy), meanwhile, will inspect the runway and prepare for flights. The reinforcements, numbering several hundred, would add to an estimated 1,500 US soldiers at the airport.

US military sources said that at least one American was killed in fighting for the airport and four were wounded. Iraq said its forces had destroyed 11 US tanks and eight armoured personnel carriers. It claimed that battles were still going on.

American commanders said they had seen no sign of the "non-conventional" actions Iraq threatened to authorise against the airport last night.

To the east of Baghdad, the 1st Marine Expeditionary Force raced through Kut and reported the surrender of 2,500 Republican Guard troops before pushing on towards the capital. The Marines' 1st Division was already moving into place outside Baghdad along the Tigris river. The Nida Division of the Republican Guard became the third division no longer to "exist as an effective fighting force" during the US Marines' rapid progress towards the capital from the south-east, American military sources said.

Colonel Joe Dowdy of the Marines' 1st Regimental Combat, a key officer in the advance, was relieved of his command for unexplained reasons.

The airport was both the most significant prize, strategically and symbolically, and also the toughest fight. Having moved on to the runway on Thursday evening, the 3rd Infantry came under shellfire.The 3rd Infantry was backed up by the 82nd Airborne and the 101st Airborne, which together formed a column of armour stretching for miles on the western approach to Baghdad. They encountered only sporadic resistance on the way into the airport, which they quashed with ferocious outbursts of cannon, artillery and rockets.

From the skies, A-10 Thunderbolt "Tankbusters" fired on Iraqi tanks, reducing many of them to burning wrecks. Other warplanes bombarded airport buildings. Reporters from The New York Times saw three satellite-guided bombs strike barracks and hangars on the airport's northern side. From Iraqi positions on the ground, anti-aircraft fire shot up into the darkness. By morning yesterday, the worst of the battle was over. It was not entirely clear what toll it had taken but the 3rd Infantry said it had killed between 300 and 400 Iraqi troops.

American commanders acknowledged that sweeps of the airport buildings were still going on. They also said they had become aware of a complex of underground tunnels and bunkers that might still contain Iraqi troops and special forces.

The symbolic value of the airport became apparent as both sides rushed to make public statements. In Qatar, the US Central Command spokesman, Brigadier General Vincent Brooks, announced that the airport had been renamed Baghdad international airport instead of Saddam international airport. "It is a gateway to the future of Iraq," he said.

The Iraqis, meanwhile, claimed to have inflicted significant damage on the US forces. A statement claimed 11 tanks and eight armoured personnel carriers had been destroyed and said the battle was still raging late yesterday. The Republican Guard and Fedayeen, the statement said, "have sworn to inflict defeat on the enemy and to teach them a lesson whereby they will know what kind of men we are".

For the US 3rd Infantry, Baghdad's airport has been the goal since the war began. The plan now is to use it as a forward base of operations, especially for the 101st Airborne, whose helicopters and swift-moving combat specialists could prove essential if the battle for Baghdad turns into a bitter street-by-street struggle.

"We're fighting in urban terrain now and to be effective in this terrain you need light infantry forces. This is their forte and they provide us additional capabilities," said Colonel John Peabody, an engineer brigade commander.

How quickly that happens depends, in part, on the level of resistance from the Republican Guard. US officials claim to have reduced at least two divisions, the Medina and the Nida, to scrap metal, and US warplanes have destroyed a Special Republican Guard complex on the east side of the airport.

How many highly trained Iraqi troops have moved into the capital for a last stand is not clear. US troops also remain fearful of chemical attacks as they mass outside the city.

And last night, the British commander in the Gulf, Air Marshal Brian Burridge, speculated that President Saddam may attempt to use human shields to retake the airport. "He could use a human tide," Air Marshal Burridge said. "We had signs last [Thursday] night there were loudspeakers in south-west Baghdad signalling people should rise up and march on the airport."