Turkish troops began entering northern Iraq early Saturday [Baghdad time], according to CNN.

The report came in after the United States and its allies, nearly 36 hours after the declaration of hostilities, on Friday evening unleashed the much talked about 'shock and awe' campaign against Iraq.

The capital Baghdad came under massive bombardment, with coalition jets carrying out more than 1000 sorties.

Many parts of Baghdad turned into an inferno, sending plumes of smoke into the sky.

Among the many targets were President Saddam Hussein's palaces in the city, according to BBC.

The compound of the elite Republican Guards was also bombed.

The Iraqis, in response, fired anti-aircraft guns.

A correspondent of Al-Jazeera television network perhaps best summed up the situation in the capital: "Baghdad is burning. What more can we say."

The northern cities of Mosul and Kirkuk, where US forces were trying to secure control of vast oilfields, also came under massive attack.

The coalition will hit many targets in the ongoing campaign, US joint chiefs of staff, General Richard Myers, said at a Pentagon briefing.

"At this stage our ground forces have pushed about 100miles [160km] into Iraq," he said.

"In the last 24 hours, special operations forces have seized an airfield [identified as H-2 and H-3] in western Iraq and secured border positions in several key locations.

"On the ground, the 1st Marine Expeditionary Force, along with our coalition partners, crossed into Iraq and they have now secured the port city of Umm Qasr," he said.

CNN reported that about 250 Iraqi soldiers surrendered to the US Marines and about 30 or so to the British forces at Umm Qasr, from where aid for the Iraqi civilians can be imported.

After the capture of Umm Qasr, the coalition forces moved towards Basra, Iraq's second largest city, according to BBC.

"They have also secured the main oil fields along the al-Faw waterways and they have moved into the southern Iraqi oil fields," Myers said.

"These fields, if we are successful, should be secured later today," he said.

The al-Faw peninsula is important because it is Iraq's only access to the Persian Gulf and the gateway to Iraq's southern oil fields.

US officials also said the Iraqis had torched several wells in the area.

Secretary of Defence Donald Rumsfeld, who was standing alongside Myers, said, "The regime is starting to lose control of their country.

"They're beginning to realise, I suspect, that the regime is history."

Rumsfeld said the latest attacks were launched after senior Iraqi officers failed to turn against Saddam after the initial strikes.

"What we've done so far has not been sufficiently persuasive," Rumsfeld said.

Meanwhile, Bradley fighting vehicles, M1A1 Abrams tanks and other vehicles from the 3rd Squadron of the US Army 7th Cavalry Regiment, lead element of the 3rd Infantry Division, raced toward Baghdad, CNN said.

The caravan had reached the centre of Iraq and was going towards the town of Nasiriya, according to BBC.

But the gains came at the cost of two US Marines, who died in action in southern Iraq.

Early in the morning, a US Marine CH-46 helicopter crashed in northern Kuwait, killing 8 British military personnel and four American crewmembers, the Pentagon said.