Cameron urges vigilance after bin Laden death

Prime Minister, David Cameron, speaks on the BBC's Andrew Marr Show, in London May 1, 2011.

LONDON (Reuters) - Prime Minister David Cameron said on Monday that Britain must remain vigilant against potential reprisals following the killing of al Qaeda leader Osama bin Laden in Pakistan by U.S. forces.

British embassies have been asked to review their security measures, but the formal threat level at home was unchanged.

Cameron, who will make a statement to parliament on Tuesday, said in a televised reaction from his official country residence Chequers that bin Laden's death would be "welcomed right across our country."

"Of course, it does not mark the end of the threat we face from extremist terror. Indeed, we will have to be particularly vigilant in the weeks ahead. But it is, I believe, a massive step forward," he said.

A government crisis committee met late on Monday to discuss bin Laden's death.

"The group welcomed (President Obama's) announcement and agreed it was an important step forward in the fight against terror," a spokeswoman for Cameron's office said in a statement.

"They agreed to continue to make every effort to counter terrorism and extremism."

The group, known as "Cobra," convenes in emergencies and brings together officials from various departments.

Separately, in phone calls with the leaders of Afghanistan and Pakistan, Cameron said Britain would work "extremely closely" with both countries "to tackle the terrorist threat from Al Qaeda and from the Taliban," Cameron's office said in a statement.

Foreign Secretary William Hague said he expected heightened vigilance at posts abroad for "some time to come."

"There may be parts of al Qaeda that will try to show that they are still in business in the coming weeks as indeed some of them are," Hague told BBC Radio 4, during a trip to Cairo.

The Foreign Office advised Britons overseas to avoid large crowds and public events, and Defence Secretary Liam Fox said he had directed his department to "maintain a high level of vigilance in all UK defence facilities at home and abroad."

Britain remains at its second-highest threat level of severe, meaning a militant attack is considered highly likely.

LONDON ATTACK

Cameron said bin Laden, who was killed on Monday in a firefight with U.S. forces in Pakistan, had been responsible for ordering the death of many British citizens both at home and in other parts of the world.

In July 2005, four young British Islamists inspired by al Qaeda killed 52 commuters in suicide bomb attacks on the capital's transport network. Sixty-six Britons died in the attacks of September 11, 2001, on New York and Washington.

"Above all today we should think of the victims of the poisonous extremism that this man has been responsible for," Cameron said.

Former Prime Minister Tony Blair, in power at the time of the 2005 and September 11 attacks, said in a statement: "The operation shows those who commit acts of terror against the innocent will be brought to justice, however long it takes."

Obama phoned Cameron early on Monday, a Downing Street spokeswoman said.

Bin Laden was killed in a compound in Abbottabad, north of Islamabad, despite the general assumption that he had been in the mountainous region between Afghanistan and Pakistan.

Fox said it was important Pakistan was fully committed to the battle against international terrorism and he hoped the killing would see a renewed commitment because "the threat from al Qaeda will not go away with the death of one man."

"In Pakistan, it is essential that they have a battle against both the Pakistan Taliban and the Afghan Taliban, it is not sufficient to choose just one or the other."

Hague said Britain's work in Afghanistan, where it has 9,500 troops, would remain "phenomenally difficult and must go on."

(Additional reporting by Adrian Croft and Karolina Tagaris; editing by Tim Pearce)