IRAQ was under attack early today as the allies launched a surprise dawn raid on Baghdad. Air raid sirens sounded at 2.30am and 20 minutes later explosions were heard. A huge pall of smoke could be seen to the south of the city.

With the 1am deadline for Saddam Hussein to flee Iraq having passed an hour and a half earlier, it had appeared that the assault was likely to wait until later today.

British and US warplanes had fired the first shots in the inevitable war earlier in the evening but the expected assault failed to materialise.

But as daylight broke, anti-aircraft fire lit up the sky and the Pentagon confirmed that the main assault was under way.

President George Bush was due to address the nation shortly after the dawn attack.

Earlier, the Allied aircraft had attacked long-range artillery and missile positions in southern Iraq as 250,000 coalition troops stood poised for battle.

Some of the warplanes were launched from the USS Kitty Hawk in the Gulf. They included two F-14A Tomcats and eight FA-18 Hornets. The Pentagon said the artillery units may have had chemical or biological weapons which could be used on US and UK troops.

Special forces were also believed to be operating in Iraq, with several explosions seen from over the border in Iran.

Last night, Iraq claimed that the warplanes had attacked Basra International Airport.

The Iraqi News Agency reported that aircraft attacked civilian and military installations at Anbar, Basra and Kut.

But Lieutenant Nicole Kratzer, a spokeswoman for Carrier Air Wing Five, the airborne strike force aboard the Kitty Hawk, said their targets were "an Iraqi intelligence facility and mobile missile sites".

She said the bombs were laser-guided, precision weapons but did not elaborate.

As the 1am deadline passed for Saddam to leave his country, 17 Iraqi soldiers handed themselves over to US troops on the Kuwaiti border.

There were also reports of mass desertions from the Iraqi army in the north of the country. Up to three-quarters of some regiments were said to have fled on the border with Kurdistan.

In a highly significant development in Baghdad, a half-brother of Saddam who is regarded as one of the the dictator's closest advisors, has fled in the past week to Syria.

Sab'awi Ibrahim Hasan Al-Tikriti, who is regarded in the US as a possible war criminal, has sought refuge in Damascus.

His flight from Baghdad suggests "fractures developing within the regime", according to an intelligence report.

"We are looking at wholesale desertions in some areas," said an intelligence officer.

"In the southern area, where there are six Iraqi divisions, 50 per cent of their officers are planning to surrender once the campaign opens."

Earlier, British and US armoured units moved up to their forward positions on the border awaiting the final order to advance.

Advanced US forces were already reported to have entered the demilitarised zone separating Iraq and Kuwait.

Last night, a vast array of Allied troops and military hardware were massed on the southern edge of Iraq.

All are now only waiting for the final "execute order" - the signal to advance and launch the invasion.

Throughout the day, final preparations were being made by troops across the whole of the Gulf region.

Servicemen and women posted their final letters and made last calls home before communication lines were shut down.

At secret briefings generals and intelligence experts studied 11th-hour reports of Iraqi troop movements. Latest intelligence reports indicate troops on the ground could face a last-ditch chemical weapons assault from Saddam Hussein's desperate regime.

British service personnel have now been ordered to carry protective anti-chemical warfare suits, as well as respirators, with them at all times.

Decontamination units have been deployed on lorries to forward positions, with Army personnel issued with rubber protection suits and a high-pressure spray of a decontamination solvent.

Anti-nerve gas treatment packs and morphine have also been issued to troops.

Chemical attack exercises were carried out with cries of "Gas! Gas! Gas!" followed by a flurry of activity as hundreds of troops dropped to their knees, backs to the prevailing wind and then donned their black rubber respirators.

Back in Britain there were also visible signs of war. Giant US B-52s at RAF Fairford in Gloucestershire were being made ready.

The bombers can deliver a payload of cruise missiles on Baghdad within six hours of taking off.

In London, Tony Blair led MPs in wishing troops well in the coming conflict and sought to switch attention to post-Saddam Iraq.

Speaking during Prime Minister's Questions in the Commons, Mr Blair said: "Our quarrel is not with the Iraqi people. The Iraqi people are the principal victims of Saddam Hussein."

White House spokesman Ari Fleischer warned the American public that they needed to be prepared for casualties.

"Americans should be prepared for what we hope will be as precise, short a conflict as possible," he said.

"But there are many unknowns and it could be a matter of some duration. We do not know," he said.

"Americans ought to be prepared for loss of life."

Britons around the world were warned by the Foreign Office last night that they face a heightened risk of terrorist attacks

20/03/2003