Colonel Will Grimsley said the tank battalion task force from the 3rd Infantry Division punched their way toward the heart of Baghdad on a road leading from the capital's main airport, 20 kilometers (12 miles) to the southwest.

Grimsley, commander of the division's First Brigade, said the raid was a show of force a day after US forces seized control of most of the airport as a key prize in their 16-day-old campaign.

"It's called 'let me poke you in the eye because we can and you can't do anything about it'," the colonel said, adding that the move "started at first light."

Grimsley said elements of the division's Second Brigade had come under rifle fire and attack by rocket-propelled grenades (RPGs) as they moved on the heart of Baghdad.

A US tank commander was shot and killed and two other soldiers were wounded in the drive through the center of Baghdad, an infantry officer said.

"We had one KIA (killed in action)," Colonel David Perkins, commander of the 2nd Brigade of the 3rd Infantry Division, told AFP.

Asked how he was killed, Perkins said the commander had sustained a "head wound."

The second soldier had suffered chest wounds while the third had been shot in the shoulder, Perkins added.

At the US military's forward command headquarters near Doha, Qatar Navy Captain Frank Thorp signalled that US infantry troops were likely to hold their positions in the middle of the city.

"This wasn't a patrol -- go in and come out," he said.

"This is part of the (US Army's) Fifth Corps moving into the city.

"We've moved pretty much into the middle of the city. What we have are elements of the Fifth Corps who moved up from Karbala a couple of days ago and have been south of the city and have now moved up into the city."

He said "significant numbers" of US forces were taking part in the operation and had encountered "sporadic resistance" from what he described as remnants of the Al-Nida and Baghdad Divisions of the elite Republican Guard Corps.

"It was done in a deliberate way," Thorp said. "When we had the opportunity we took it and moved forward into the middle of the city."

US forces took control of the airport on Friday -- renaming it Baghdad International Airport.

Lieutenant Colonel Scott Rutter, commander of the 2-7 Infantry Battalion of the 1st Brigade, said that clashes with Iraqi troops continued around the airport late into Friday.

"Between 100-120 enemy" fighters had been killed by his battalion in clashes on Friday afternoon and evening after they launched a counter-offensive, said Rutter.

Six Iraqi T-72 tanks had been destroyed in the exchanges by a combination of javelin laser-guided missiles and other conventional anti-tank weaponry around the sprawling airport complex, he added.

They also destroyed five Iraqi armoured personnel carriers and "teams" of Iraqis firing RPGs.

SPACE.WIRE