Coalition bombs and missiles have struck Iraqi presidential sites in central Baghdad and pounded Republican Guard divisions just south of the city in a round-the-clock bombardment.
Air strike on Baghdad: Heavier bombs are being used
US President George Bush said there would be no pause in the assault, promising the Iraqi people that "we are coming and we will not stop, we will not relent until your country is free".
The ground war moved closer to Baghdad on Monday, with fierce skirmishes between US troops and Republican Guard units at Hindiya, about 80 kilometres (50 miles) south of the capital, the US military said.
We're coming with a mighty force to end the reign of your
In an incident which could undermine coalition efforts to win hearts and minds, seven Iraqi women and children were killed by US troops when their car failed to stop at a checkpoint.
The BBC's Paul Wood in Baghdad says presidential palaces on the banks of the River Tigris were targeted in the latest air raids.
Coalition forces are trying to hit Iraqi command and control facilities and symbols of the regime, he says.
The Pentagon says coalition aircraft have dropped more than 3,000 precision-guided or smart bombs in the past three days, causing a "very significant weakening" of Iraqi forces.
But so far the Iraqi leadership shows no sign of crumbling from within, our correspondent says.
The fighting at Hindiya, on the Euphrates river, was reported to be the closest engagement yet to the capital.
US forces said many Iraqis and at least one American were also killed in fierce fighting near Hilla, on the same battle front.
The US attacks are believed to be aimed at testing the strength of the units dug in on the approaches to Baghdad.
After a series of fierce clashes UK Royal Marines tightened their grip around the southern city of Basra on Monday, moving into al-Zubayr and Abu al-Qassib - a village just one mile from the city.
Other key developments:
The US is sending about 5,000 reinforcements to the strategic southern city of Nasiriya to support the 7,000 marines facing stiff resistance there
UK Defence Secretary Geoff Hoon says coalition forces now hold about 8,000 prisoners of war in Iraq - but so far, no high-ranking Iraqi political or military figures have surrendered
Iraqi authorities say their forces have killed 54 US and UK soldiers in the past 24 hours - but there is no independent confirmation of the claim
US military says it is denying freedom of
movement throughout Iraq's western desert - and its aircraft struck at paramilitary forces in the western town of Rutbah
- US Secretary of State Colin Powell heads for Turkey on Tuesday for talks on US plans for Iraq, amid continuing tensions with Ankara
Hindiya bridge: Civilians were caught in crossfire
State-run Iraqi television was off air for a few hours on Monday following overnight missile strikes. But later it showed Saddam Hussein chairing a meeting of top aides, including his sons Qusay and Uday.
The US military says three-quarters of the coalition air strikes are now targeting three Republican Guard divisions around Baghdad: the Hammurabi, to the north, west and south; the Medina, to the south; and the Baghdad, deployed south-east of the capital, around Kut.
According to General Richard Myers, chairman of the US Joint Chiefs of Staff, a week of heavy bombing has reduced some Republican Guard units to less than half their normal strength.
HUMAN COST OF WAR
Iraq: At least 589 civilian deaths, military deaths unknown
US: 50 dead (including 11 in accidents, 2 under investigation), 13 missing
UK: 25 dead (including 15 in accidents, 5 to 'friendly fire')
*Figures from each government
In the south, US marines have stepped up their attacks on Iraqi forces still holding out in Nasiriya.
The BBC's Andrew North says marines are targeting all buildings associated with the ruling Baath Party security apparatus, he says.
US commanders say the fighting in Nasiriya has proven especially difficult because of their wish to avoid hurting civilians.
US marines have found stashes of weapons, ammunition and chemical protection suits at Iraqi camps in the Nasiriya area.