"Right now elements of the 2nd Brigade, 3rd Infantry Division -- that is a tank unit -- are rolling in the heart of Baghdad itself. They are deep within the city limits," the US-based network's correspondent on the city's outskirts, Walter Rodgers, said in a live dispatch.

"They are encountering resistance ... stiff resistance at times," he said, citing US military sources.

The Iraqi defenders were using 20 mm anti-aircraft guns in "direct fire mode" to pound US forces with shrapnel, as well as RPGs and small-arms fire, he added.

The resistance "may have slowed progress but there is continuing progress" into the capital, he said, adding that it must have been "quite a jolt" for Baghdad residents as they woke up to see coalition forces on their doorsteps.

The incursion into Baghdad followed the announcement by US commanders that they had seized control of the capital's international airport, just 20 kilometres (12 miles) from the city centre.

SPACE.WIRE