United States and British forces have launched massive aerial assaults on targets in Baghdad and
beyond in a major escalation of the war.
Bombs rained down on the Iraqi capital, as the US unleashed what it calls its "shock and awe" strategy.
Several hundred targets would be hit in the coming hours, the US Defence Department said.
The BBC's Paul Wood in Baghdad says the targets there included President Saddam Hussein's palaces.
Offices of the Foreign Ministry and the Deputy Prime Minister were also ablaze.
US Defence Secretary Donald Rumsfeld said the scale of the assault was intended to show the Iraqis that Saddam Hussein was finished.
"The [Iraqi] regime is starting to lose control of their country," he said.
Air strikes have also hit the city of Mosul in the north.
The BBC's John Simpson, reporting from the region, said the skyline was lit up many times.
Several explosions have also been reported in another northern city, Kirkuk, where American forces are trying to secure control of vast oilfields.
As the bombardment continued, Iraqi Defence Minister Sultan Hashim Ahmed told a news conference that "no force in the world" would conquer Iraq, the AFP news agency reports.
US-led ground forces have advanced
about 160 kilometres (100 miles) into Iraq, the chairman of the US joint chiefs of staff, General Richard Myers, told a news conference in Washington.
Coalition forces are also moving on Iraq's second city, Basra, according to the UK Ministry of Defence.
The advance on the city came after US Marines reached Iraq's only deep-water port at Umm Qasr in the south-east.
"Umm Qasr has been overwhelmed by the US Marines and now is in coalition hands," Admiral Sir Michael Boyce, chief
of the UK General Staff, told a news conference in London.
However, the BBC's Adam Mynott, who is with the troops on the ground, says that while coalition forces undoubtedly have the upper hand, they do not have total control of Umm Qasr.
The port in the south-east is seen as key for the importing of aid for the Iraqi civilian population.
The US 3rd Infantry Division has moved into the centre of Iraq, close to the city of Nasiriya - a key crossing point over the Euphrates river on the way to Baghdad.
The BBC's Gavin Hewitt says there have been some clashes between American forces and Iraqi forces followed by quite a strong American bombardment of the area around the city, he says.
In other reported advances, US defence officials said key airfields known as H2 and H3 in western Iraq were taken over by coalition forces.
The BBC's defence correspondent, Jonathan Marcus, says these are possible jumping-off points for a multi-pronged assault on Baghdad.
Earlier in the day, British troops took control of key oil installations on the nearby al-Faw peninsula after a brief firefight - an operation designed to prevent the release of oil into the Gulf by retreating Iraqi forces.
But Admiral Boyce said that elsewhere in Iraq seven oil wells had been set alight by Iraqi forces, down from an earlier estimate of 30.
In other developments:
- Turkey agrees to let US warplanes fly over its territory, but the Turkish Foreign Minister, Abdullah Gul, says they will send troops into northern Iraq, despite Washington's disapproval.
- Saddam Hussein decrees that any Iraqi who captures an enemy soldier will get a reward of about $32,000, Iraq's government-run news agency reports. The reward for killing an enemy soldier was put at about $16,000.
- Two US marines are killed in southern Iraq, hours after eight British and four American servicemen die in what is believed to be a helicopter accident
- Anti-war protests continue around the world, with at least two people - one of them a policeman - killed in clashes in the Yemeni capital, Sanaa
- Patriot missile defence systems shoot down more Iraq missiles heading for Kuwait following Thursday's attacks
- French President Jacques Chirac says he will not accept a US-British post-war administration of Iraq, adding that the UN is the only body which can be responsible for rebuilding the country.
US President George W Bush on Friday said the war was "making progress".
He added: "We will stay on task until we've achieved our objective, which is to rid Iraq of weapons of mass destruction and free the Iraqi
people so they can live in a society that is hopeful, democratic,
and at peace in its neighbourhood."
In official responses to the coalition attack, Iraqi ministers have issued defiant statements.
The Information Minister, Mohammed Saeed al-Sahhaf, told journalists that television pictures showing Iraqi troops surrendering were falsified.
He also said that Iraqi forces had shot down a coalition fighter jet. This has been denied by the American military.
Interior Minister Mahmoud Dhiab al-Ahmed described the US as a "superpower of villains", comparing President Bush to the 1920s American gangster, Al Capone.