With US troops reported to be just 15 kilometers (nine miles) from the center of Baghdad, coalition warplanes maintained their bombardment of the city overnight.

Several loud explosions rocked the capital and artillery fire was heard on the southern outskirts, but the targets were not immediately apparent. One downtown building was set ablaze, correspondents said.

After a lull of a few hours, the bombing of the southern rim began again around 8:00 am (0400 GMT). But life in central Baghdad nonetheless displayed a semblance of normality early Friday, with buses and cars on the streets.

Late Thursday, most of Baghdad was plunged into near total darkness following a power outage, although the US military said its forces had not targeted the power grid.

The British press said US and British special forces had taken advantage of the blackout to enter the city for covert operations.

By dawn Friday, US forces "controlled probably 80 percent" of Saddam International Airport, 20 kilometers (12 miles) southwest of the capital, according to Major John Altman of the 3rd Infantry Division's 1st Brigade.

But US troops were nonetheless locked in an exchange of heavy gunfire and artillery with Iraqi forces around the airport. The fighting flared around 7.30 am (0330 GMT), with Iraqi units shelling US positions inside the complex.

Colonel Will Grimsley, commander of the 3rd Infantry Division's 1st Brigade said "US forces have occupied the VIP terminal at the airport."

Forty prisoners of war had been taken in the fighting, all from the Republican Guard and Iraqi special forces, he added.

Dozens of Iraqi troops were reported to have been killed or wounded in the battle for the airport, according to an Iraqi cameraman and British television correspondents. US officers said their forces sustained light casualties in the operation.

A statement attributed to Saddam Hussein and read on state television Thursday said Iraqi forces would never let their capital be taken.

"Many thousands of soldiers are defending the homeland ... and they will not allow them to go into Baghdad without defeating and repelling them," the statement vowed.

It said barely a third of Iraq's forces had yet been engaged in battle.

Iraq has repeatedly warned that the war's decisive battle will be in the capital, where it would engage US-led forces in bloody street-to-street fighting. It also says it has thousands of volunteers ready to become "martyrs" in suicide strikes.

But General Richard Myers, chairman of the Joint Chiefs of Staff, said Thursday the battle for Baghdad would not involve a traditional military siege and indicated US-led forces expected support from Shiite residents.

US military sources, meanwhile, downplayed the threat of an Iraqi chemical or biological attack, which commanders had feared could be unleased as coaliton forces approached the capital.

"Now that we have penetrated Baghdad's outer ring, the likelihood is negligible," Captain Adam Mastrianni, the intelligence officer of the 101st Airborne Division's Aviation Brigade, said Thursday.

He said that as Iraqi troops did not resort to chemical arms after US forces reached Karbala, 100 kilometers (60 miles) south of Baghdad, and after their advance to the outskirts of the capital it was unlikely such weapons would be used now.

In the southern theater of the conflict British forces battling to take control of Basra came under fire Thursday as they made further incursions into the main southern city where officials warned some 1,000 Iraqi militiamen were still holding out.

SPACE.WIRE