'Our target was terror. Our mission was clear,' he said from the Oval Office, in a second major address to the country this week. 'The countries that persistently host terrorism have no right to be safe havens. No religion condones the murder of innocent men, women and children.'

Between 75 and 100 Tomahawk missiles were fired from six US warships and a submarine at 'terrorist facilities' in Afghanistan and in Sudan in retaliatory raids against the embassy bombings in east Africa, which killed at least 263 people, among them 12 Americans.

The president announced the attacks on the same day that the former White House intern Monica Lewinsky testified for a second time to the grand jury that is investigating her affair with him.

The Clinton adminstration vowed the attacks were not an isolated raid but part of an ongoing assault against the resurgence of anti-American atrocities.

'We are not going to take an ad hoc approach to this. This is a very serious battle . . . We have to organise in the long run to confront a serious threat to our way of life,' said Madeleine Albright, the secretary of state. Intelligence reports had indicated what national security adviser Sandy Berger called 'concrete information' that the embassy bombings were about to be repeated.

The missiles struck at a suspected chemical weapons factory in Khartoum, Sudan, and the Afghan base of the Saudi millionaire Osama bin Laden , the prime suspect in the embassy bombings. He escaped unharmed.

The Afghan target was a compound of six buildings at Khost, near the Pakistani border, comprising training camps and an arsenal of weapons and ammunition.

The sites are part of what intelligence reports called the largest and most extensive Sunni Muslim 'terrorist university' in the world. Officials said the site operated with the blesssing - if not the outright support - of Afghanistan's Taliban regime.

In Sudan the target was the Shifa pharmaceutical plant, which intelligence reports say is a factory manufacturing chemical weapons.

A senior US intelligence official said the Sudanese target was guarded by the military and was used to make chemicals for the deadly nerve gas VX.

The intelligence reports were passed on to the president at the end of last week, when the decision to strike was made.

There was outrage in the Arab world as television reports from Sudan showed extensive damage, casualties and fires raging more than an hour after the missiles struck. The timing of the strikes - 7.30pm in Sudan and 10pm in Afghanistan - was chosen to reduce the risk of civilian casualties in Khartoum, US intelligence officials said.

Mr Clinton, who returned from his holiday retreat within hours of the bombing, said he had ordered the strikes not only in response to the embassy bombings but also to pre-empt more attacks on Americans.

'Today we have struck back,' he said. 'We have convincing evidence these groups played the key role in the embassy bombings in Kenya and Tanzania. Terrorists must have no doubt that in the face of their threat America will protect its citizens.'

There were few immediate reports on the success of the strikes or of casualties in either of the operations. An hour after the attack, the Taliban flashed a statement claiming that Mr Bin Laden was alive and well.

'Bin Laden is safe and no damage has been done to any of his companions,' it said. An outraged Sudanese interior minister, Brigadier Abdel-Rahmen Mohammed, said the bombed factory produced medicine. 'It is not chemical weapons. it is a factory for medical drugs. We have no chemical weapons factory in our country.'

The attack sparked fury in Khartoum. Angry demonstrators took over the empty US embassy. State-run television showed hundreds of people scaling the wrought-iron fence around the building in the heart of the capital.

The state department ordered the building closed after the August 7 bombings of embassies in Nairobi and Dar es Salaam.

In London, the Prime Minister, Tony Blair, supported the US action without qualification. 'I strongly support this American action against international terrorists. Terrorists the world over must know that democratic governments will act decisively to prevent their evil crimes,' he said. The attacks were supported by the Republican Party leadership, despite accusations that the president was seeking to distract attention from the Lewinsky scandal.

The attacks were planned under a shroud of utter secrecy. One of the advantages of using cruise missiles is that there is no outward sign of imminent action.

It emerged yesterday that only a core of military and political leaders knew what was about to be unleashed on Mr Bin Laden's headquarters.

Mr Bin Laden has been targeted by US intelligence since a blanket fatwa was issued in February against all American citizens. The CIA warned that the edict would 'explicitly justify attacks on American civilians anywhere in the world'.

The reasons

President Clinton gave four reasons for the strikes:

1. 'We have convincing evidence these groups played the key role in the embassy bombings in Kenya and Tanzania.'

2. 'These groups have executed terrorist attacks against Americans in the past.'

3. 'We have compelling information that they were planning additional terrorist attacks against our citizens and others with the inevitable collateral casualties we saw so tragically in Africa.'

4. 'They are seeking to acquire chemical weapons and other dangerous weapons.'