PRIME Minister Tony Blair's war cabinet was meeting today after a second round of military strikes against Osama bin Laden and his Taliban protectors.

Twenty US warplanes and naval forces firing Tomahawk cruise missiles attacked targets across Afghanistan last night.

Another 37,000 packages of humanitarian food rations were also being air-dropped over the country.

Doctors at Wazir Akbar Khan Hospital said four people were killed last night when three bombs were dropped on the capital Kabul.

A Taliban-linked news agency said a 400-bed women's hospital in Kabul had been bombed but made no mention of any damage.

The strikes were unleashed as it was confirmed that British journalist Yvonne Ridley, arrested for illegally entering the country, had been released by the Taliban and handed over to Pakistani officials.

Unlike the first night of action, British forces were not involved in the raids, thought to have hit targets around Kabul, Mazar-e-Sharif and Kandahar.

However, their future role seemed certain to be under discussion as Mr Blair convened his war cabinet for the first time.

Jack Straw today told his Blackburn constituents to be "calm but vigilant" as the war against international terrorism escalates.

Speaking before he went into the first meeting of the War Cabinet, the Foreign Secretary said: "I have a message for people of all faiths in Blackburn.

"The military action which the UK is now involved is necessary given that the Taliban refused a more peaceful route by handing over Osama bin Laden.

"The action is being conducted with great care.

"The targeting, to try and avoid civilian casualties, is being very carefully planned as I know personally.

"The actions are proportionate and appropriate.

"We have no specific information regarding terrorist threats to people in the UK.

"I would urge people in Blackburn to remain calm but also to be vigilant."

Deputy Prime Minister John Prescott; Chancellor Gordon Brown; Chief of Defence Staff Admiral Sir Michael Boyce; Home Secretary David Blunkett; Leader of the Commons Robin Cook; and International Development Secretary Clare Short have been appointed to the inner circle along with Mr Straw.

Defence Secretary Geoff Hoon was absent - he was having talks in Moscow with his Russian counterpart.

But Mr Hoon confirmed plans were being drawn up to send in ground troops - possibly including a British force - in the wake of the air strikes.

However he warned that if the Taliban regime collapsed and Afghanistan descended into civil war it may be too dangerous to deploy land forces.

"It is perfectly possible that the impact of these initial strikes and the ones that are likely to follow will have such a seriously destabilising impact on the Taliban regime that the use of ground troops may not be possible, certainly not in a hostile environment," he said.

The Prime Minister was expected to begin by bringing them up to date on the latest US action.

In an emergency statement to MPs last night Mr Blair said Sunday's strikes seemed to have successfully hit bin Laden's al Qaida terrorist network and Taliban military sites.

But he warned: "We are in this for the long haul. Even when al Qaida is dealt with, the job is not over.

" The network of international terrorism is not confined to it.

"We will continue to act, with steadfast resolve, to see this struggle through to the end and to the victory that would mark the victory not of revenge, but of justice over the evil of terrorism."

And the US formally notified the United Nations Security Council last night that the counter-terrorism offensive launched in the wake of the September 11 atrocities could be extended beyond Afghanistan.

Senior officials said a legal document sent to the Security Council described attacks on Afghanistan as an act of self defence under the UN Charter and reserved the right to extend strikes to other countries harbouring terrorist cells.

US officials said 10 of them B1 and B2 bombers and 10 carrier-launched fighter-bombers took part in last night's action, while Tomahawk Cruise missiles had been launched from American warships.

Power was cut in Kabul soon after the latest barrage began, while Taliban officials said that other strikes were taking place at the movement's stronghold in Kandahar.

But Ms Short stressed the need to strictly limit the military campaign and not widen the objectives to include other "trails that need to be corrected over time.

"We must focus so that it's a just war and that it's focused and that there are no civilian casualties and that we keep together the global coalition," she said.

She added the allies should "go after those who perpetrated the monstrous act that took place in the United States of America and not look for all trails that need to be corrected over time".

The campaign needed to be focused in order to "keep the global coalition together".