Britain said Thursday's attack on Iraq would quickly widen and denied that the United States had taken its main ally by surprise with its pre-dawn raid on Baghdad. The United States began the war against Iraq by hitting selected targets in the outskirts of Baghdad and President Bush said the U.S.-led coalition planned to use decisive force to remove President Saddam Hussein from power.

But a military source told Reuters that the Americans had struck Iraq without British involvement and that the Ministry of Defense was "in effect, not part of the planning."

Aides had been told late on Wednesday that no action was expected overnight and the government admitted Britain had been informed of the U.S. strike only hours before it was launched.

But Britain, which has committed 45,000 troops to help the United States oust Saddam, said it had not been sidelined.

"I was well aware that this target was to be addressed," said Defense Secretary Geoff Hoon. "It is clear you will not have to wait very long (for a wider military campaign)."

Hoon, speaking just before Prime Minister Tony Blair summoned his top ministers for a war cabinet, said British troops were on a "very, very high" state of alert.

He said there was a clear timetable for the next wave of attacks and that he knew when the big push would start.

"These are the opening stages of the military operation and I anticipate that in time we will see further evidence that this is part of a continuing campaign," he said in one of a series of interviews.

A U.S. military commander told reporters in Kuwait that limited U.S. air raids will continue against Iraq for the next two or three days as part of a "pre-battle" plan ahead of a major assault.

ALERT

Heathrow Airport, close to London, was put on full alert amid fears of terror reprisals. Armed police patrolled the four terminals and staff were put in a state of "heightened awareness."

British Airways had already canceled all flights to Kuwait and Israel and was reviewing other routes.

The attacks also kicked Britain's large anti-war movement into action. The main Stop the War Coalition said it expected "thousands and thousands" of people to protest during the day over a war that has pitted Blair against both the public and large sections of his own Labour party.

"This is a day of shame for Britain...an outrage against world peace," spokesman Andrew Burgin said.

The Stop the War group said "big" demonstrations and roadblocks had already begun on Thursday morning in the northern cities of Bradford and Leeds.

More than one million Britons marched in a recent anti-war demonstration in London against staunch British support of the U.S. policy, which has pitted Blair against European allies.

A spokesman said Blair would make a statement later on Thursday. After the war cabinet met, he was due to hold a full cabinet later in the morning.

PHOTO CAPTION

British troops of the 16 Air Assault Brigade are seen in the Kuwaiti desert. Geoff Hoon confirmed British forces were involved in initial strikes on Iraq (AFP/File)