Britain and America last night launched strikes against Osama bin Laden's terrorist network and Afghanistan's ruling Taliban regime, in a long-awaited reprisal for the September 11 atrocities.

The allied attacks - the first wave of an international fightback against terrorism - began with 50 Tomahawk cruise missiles launched from British and American submarines based in the Arabian Sea at the start of Operation Enduring Freedom.

Explosions were reported in the Afghanistan capital Kabul, the southern city of Kandahar and in Jalalabad.

Prime Minister Tony Blair in Downing Street and President George Bush in Washington gave confirmation of the strikes.

In Karachi, Pakistan, Rehmatullah Kakazada, the consul-general for Afghan-istan's ruling Taliban, condemned the attack and said: "We are ready for jihad (holy war)."

A Pentagon official said targets for last night's strikes included air defences, military communications sites and terrorist training camps inside Afghanistan.

"We are supported by the collective will of the world," said President Bush in an address from the White House.

Mr Blair said: "Military action against targets inside Afghanistan have begun. I can confirm that UK forces are engaged in this action.

"I want to pay tribute at the outset to Britain's armed forces. There is no greater strength for a British Prime Minister and the British nation at a time like this to know that the forces we are calling upon are amongst the best in the world.

"They and their families are of course carrying an immense burden at this moment and will be feeling deep anxiety, as will the British people, but we can take great pride in their courage, their sense of duty, and the esteem with which they are held throughout the world."

He added: "This is a moment of utmost gravity for the world. None of the leaders involved in this action want war. None of our nations want it. We are peaceful people.

"But we know that sometimes to safeguard peace, we have to fight.

"Britain has learnt that lesson many times in our history. We only do it if the cause is just. This cause is just."

Mr Blair said British air forces would be used in the operation in the days to come.

"The US are obviously providing the bulk of the force required and leading the operation," he said.

"But this is an international effort. As well as the UK, France, Germany, Australia and Canada have also committed themselves to take part in it."

Downing Street later announced that Parliament would be recalled today, with a statement from Mr Blair at 6pm.

The Taliban regime last night declared the assault a "terrorist attack" and vowed that America "will never achieve its goal".

Bin Laden, in a video claimed to have been taken yesterday, and shown on Al-Jazeera, an Arabic satellite station, said of the September 11 attacks: "America was hit by God in one of its softest spots.

"America is full of fear from its north to its south, from its west to its east. Thank God for that."

More details of the attacks came from Richard Myers, chairman of America's Joint Chiefs of Staff.

He said 15 bombers and 25 strike aircraft, both sea and land-based, took part in the assaults.

Mr Myers said the attacks included B-1, B-2 and B-52 bombers as well as ships and submarines in the region.

He said the B-2s flew a round trip from their base at Whitman Air Force Base in Missouri.

US Defence Secretary Donald Rumsfeld said an initial goal of the strikes was to render air defences ineffective and to wipe out the military aircraft of the Taliban.

He also stressed that allied forces were already dropping humanitarian supplies to the people of Afghanistan. He said that 37,500 rations were planned to be dropped on the first day.

The first explosions of what could be a lengthy operation were heard in Kabul at about 5.27pm UK time.

Five massive explosions shook the city, followed by the sounds of anti-aircraft fire.

Power went off throughout the Afghan capital almost immediately after the first of the thunderous blasts, which appeared to have been in the southwest of the city.

The deputy Taliban ambassador to Pakistan told US broadcaster NBC that the air strikes would unite Afghans behind the regime.

Mohammad Suhail Shaheen said: "We are victims of this expansionist antic by America.

"Such tactics will never achieve political goals. The former Soviet Union didn't achieve its political goals by invading Afghanistan.

"Throughout history in such cases, these acts have unified the Muslim nation of Afghanistan against aggressors."

Speaking from Islamabad, he said the Taliban would gain support because of the bombing.

"The Taliban are from among the people, they are not imposed, as efforts are made to impose a government on Afghanistan by a foreign ally. These attacks will further expand the support to the Taliban."

The Taliban's military forces remained safe and he said: "The army of the Islamic emirate will never be broken."

He said Mullah Mohammed Omar, the Taliban's spiritual leader, was still in charge and added: "The next step in such cases as always in Afghanistan is to defend its country and its faith."