The United States said it had begun its war against Iraq on Wednesday just minutes after several explosions were heard over Baghdad. "The opening stages of the disarmament of the Iraqi regime have begun. The president will address the nation at 10:15 p.m. EST," said White House spokesman Ari Fleischer. A handful of explosions rocked Baghdad at dawn on Thursday as jets roared overhead. Iraqi anti-aircraft batteries opened up and air raid sirens sounded.

Minutes after the first blasts occurred at 0530 local time (0230 GMT), President Bush's spokesman Ari Fleischer said: "The opening stages of the disarmament of the Iraqi regime have begun."

President Bush is due to make an address at 2215 Washington time (0315 GMT).

After the first strike, a large pall of black smoke was seen in the south of Baghdad and the city fell silent.

The attack began about 90 minutes after President Bush's deadline for Saddam Hussein to go into exile or face war expired.

As the deadline approached, US-led combat troops in the Gulf - numbering about 150,000 - took up battle positions for an imminent invasion of Iraq.

With battle looming the UN Secretary General Kofi Annan said his thoughts were with the ordinary people of Iraq as they faced the "disaster of war".

He warned the US and UK that "under international law, the responsibility for protecting civilians in conflict falls on the belligerents".

In other developments:

* Mr. Bush sends formal notification of his justification for military action to the US Congress

* UK Prime Minister Tony Blair holds a 20-minute phone call with Mr. Bush

* Germany expels four Iraqi diplomats for activities considered "incompatible with their diplomatic status"

* Iraqi Deputy Prime Minister Tariq Aziz appears on state television to refute rumours that he has fled the country or been killed

* The Turkish Government is asking parliament to allow US planes to use its air space, with a vote expected on Thursday

PHOTO CAPTION

Nosecones of F-14 Tomcat fighter jets are silhouetted as an F/A-18 Hornet fighter jet taxis after landing on the USS Kitty Hawk aircraft carrier in the northern Gulf early March 19, 2003. (Paul Hanna/Reuters)