American forces have entered "the heart of Baghdad."

It's the first clear sign of US forces in the centre of the city.

One of Saddam Hussein's main presidential compounds is said to be in American control.

Our correspondent in Baghdad, Paul Wood witnessed American troops entering the city - he says the Iraqis seemed to have been taken by surprise by the attack.

Iraqis flee US troops

The Americans are calling the attack a "show of force" and saying that they will not neccessarily hold the positions that they have taken.

Iraqis in the capital fled the tanks.

Paul Wood's reports are monitored by the Iraqi authorities

Click here to see Breakfast's interview with Paul Wood.

Paul Wood says the Eastern part of the city is at the moment is said to be untouched, while the Western side is where the American attack is concentrated.

The Iraqis claim that they have "slaughtered" American columns entering the city.

BBC Correspondent Rageh Omaar

The BBC's Rageh Omaar says the American attack included mortar rounds, heavy machine guns and small arms.

He saw "stunned and terrified" Iraqis fleeing - and Americans taking prisoners of war.

Rageh Omaar's movements are restricted and his reports are monitored by the Iraqi authorities

Click here to see Rageh Omaar's report