THOUSANDS of Iraqi troops were today surrendering to British and American troops after a night of heavy bombing over Baghdad.British and US forces continued their devastating "shock and awe'' tactics against Iraq, pummelling the capital Baghdad with a renewed wave of missile attacks.

THOUSANDS of Iraqi troops were today surrendering to British and American troops after a night of heavy bombing over Baghdad.

British and US forces continued their devastating "shock and awe'' tactics against Iraq, pummelling the capital Baghdad with a renewed wave of missile attacks.

An entire division of the Iraqi army was said to have surrendered, the Pentagon claimed.

The 8,000 or so men of the 51st Infantry Division gave up their arms as British and US forces advanced toward Basra, Iraq's second largest city.

The move raised expectations that the British-led force would soon take control of the city.

The 51st was one of the better equipped divisions, trained in Iraq's regular army forces and was the key division protecting Basra, a key transportation and oil shipment port on the Shatt al-Arab waterway leading into the Gulf.

After a night in which key targets in Baghdad were bombarded in a major escalation of military action, a further three missiles were said to have hit the city at dawn, according to Arabic satellite broadcaster Al-Jazeera.

In a separate development around 1,000 Turkish troops crossed the border into northern Iraq, angering Washington and alarming the local Kurdish population.

The US strongly opposes any unilateral move by Turkey into northern Iraq.

Turkish foreign minister Abdullah Gul said Ankara was determined to prevent any refugee exodus, as happened after the last Gulf war, and to stop any attempt by Iraqi Kurds to break away from Iraq.

The news emerged soon after Turkey relented and agreed to let US combat aircraft use its airspace.

Inside Iraq, two US Marines were killed by enemy fire, the first coalition combat deaths in the three-day-old Operation Iraqi Freedom. One died trying to secure an oil pumping station, the other fell in the battle for Umm Qasr, the port city taken after a fight.

But Iraqi troops also surrendered en masse - some so eagerly that they turned themselves in to journalists accompanying American forces.

However, the regime gave no sign of quitting. Asked whether Iraqis plan a counterattack, Information Minister Mohammed Saeed al-Sahhaf said, "Our leadership and our armed forces will decide this, in what guarantees the defeat of those mercenaries, God willing.''

The full extent of the bombing of Baghdad became apparent as day broke today.

The city was ablaze overnight with thick clouds of smoke rising high over the city as coalition warplanes and land and sea-launched cruise missiles aimed to attack 1,000 targets across the country.

In Baghdad, the first wave of missiles slammed into the capital at 9pm local time (6pm GMT) - arriving together to maximise the impact.

Mushroom clouds, sparks and palls of thick black smoke rose over the red skyline of the capital.

Saddam Hussein's Old Palace compound was among the targets hit in the terrifying onslaught which the Pentagon said marked the start of the aerial war "in earnest''.

There was speculation over the fate of Saddam with both British and US government spokesmen unable to confirm reports that he had been injured or even killed.

Al Jazeera reported: "Baghdad is burning. What more can we say?''

Two hours later, the sound of coalition warplanes was heard over the city for the first time in the current conflict, although coalition commanders were keen to stress that the "deliberate escalation'' of the campaign was aimed at specific targets of Saddam's regime.

The northern cities of Mosul, Tikrit and Kirkuk were also reported to have come under attack in the bombardment intended to paralyse the Iraqi military and force Saddam's forces to submit.

US Rear Admiral Matthew Moffit, commander of the aircraft carrier USS Kitty Hawk battle group in the Gulf, said that 320 cruise missiles were launched in the first wave against targets in and around Baghdad.

They included missiles launched from the Royal Navy nuclear-powered submarines, HMS Splendid and HMS Turbulent.

The head of US Joint Chiefs of Staff General Richard Myers told a news conference in Washington DC that "several hundred targets'' would be attacked during the course of the night.

US Defence Secretary Donald Rumsfeld said the air attacks would be of a scope and scale which made it clear to Iraqis that Saddam and his regime were finished.

The assault was preceded by the sight of eight of the giant American B-52 bombers stationed at RAF Fairford in Gloucestershire taking off for the first time since the conflict began.

The planes returned to base this morning after targeting radar defence systems in a lengthy mission lasting more than 12 hours.

Harrier GR7s and Tornado F3 fighter support aircraft were also involved in the operations.

The attacks came at the end of a day of rapid advances by British and US ground forces which took them to the outskirts of Iraq's second city, Basra.

The US 3rd Infantry Division was said to have advanced around 100 miles into Iraq towards Baghdad, prompting one military official to predict that they could be in the Iraqi capital in three or four days.

At the same time US forces supported by two battlegroups of the British 7th Armoured Brigade the Black Watch and the 1st Battalion, the Royal Regiment of Fusiliers - advanced to the outskirts of Basra with little resistance.

Both Sir Michael Boyce, UK chief of the defence staff, and General Myers expressed satisfaction at the way the campaign was progressing.

"It is very early days, but I have to say the coalition progress so far has been promising,'' Sir Michael said. "I am very encouraged by the start we have made.''

General Myers said: "We are basically on our plan but we must not get too comfortable.''