American and Iraqi forces are involved in heavy fighting in central Baghdad.
US tanks move east across the Tigris
Tanks from the US 3rd Infantry have advanced across a main bridge over the River Tigris to attack Iraqi fighters dug in on the eastern bank.
The Americans say they are now pushing from three directions to extend their control of Iraq's capital - outwards from their central enclave, from the north-west and from the south-east.
Meanwhile, US President George W Bush and UK Prime Minister Tony Blair have said they are both committed to involving the United Nations in setting up a new government in Iraq.
Other key developments:
- US military officials assess the results of an air raid on a residential part of Baghdad designed to kill Saddam Hussein, which is believed to have left at least nine civilians dead - but UK security sources believe the Iraqi leader escaped it
- The International Committee of the Red Cross expresses concern about the situation in Baghdad's hospitals, where doctors say they are being overwhelmed by the number of casualties
- Three journalists - one from Arabic news channel al-Jazeera, one from Reuters news agency and one from a Spanish television station - are killed in central Baghdad, two of them after the Palestine Hotel is hit
- British soldiers in the southern city of Basra say they must make it more secure before they can deal with widespread looting.
A BBC correspondent in Baghdad, Paul Wood, says American tanks and troops are breaking out from the positions they took in and around Saddam Hussein's main palace on Monday.
After beating off an Iraqi counter-atack, they are believed to be aiming to link up with US marines fighting their way into the city from the south-east, and more 3rd Infantry units coming in from the north-west.
US ground-attack planes and helicopters have been flying low over the city centre in support of the ground forces, firing at a wide range of targets. An attack by an A-10 'Tankbuster' aircraft left the planning ministry building on fire.
The marines have moved into the Rasheed military air base in the south-east of the city. A Reuters correspondent says they met no resistance as their armoured vehicles moved down the runway.
"We are just securing it, making sure there are no enemy
forces left in it that might be straggling behind," said US Captain
Matt Watt of the 1st Marine Expeditionary Force.
The Americans also say they are maintaining control of all major access roads around the city.
Hundreds of civilians are reported to be trying to flee the city.
Our correspondent says that while the people of Baghdad remained calm during the bombing early in the war, fear spread once American ground forces reached the gates of the city.
One US plane, an A-10, crashed near the American base at the international airport south-west of Baghdad, apparently after being shot down. US Central Command said the pilot had been rescued.
Despite the evidence of American advances, Iraqi Information Minister Mohammed Saeed al-Sahhaf has appeared again to tell reporters that the American forces are being dealt with.
"They are going to surrender or be burned in their tanks," he said.
He brushed off a suggestion that it was time for the Iraqi Government to surrender.
Meanwhile, the US military has said that more tests are required to determine if substances found at two sites in Iraq are banned chemical agents.
The US and Britain launched the war over Iraq's alleged weapons of mass destruction programme.