Al-Qaeda yesterday vowed to avenge the death of Osama bin Laden and urged Muslims to rise up against the United States, as rallies against the killing of the 9/11 mastermind in a US raid flared in the Islamic world.

“We call upon our Muslim people in Pakistan, on whose land Sheikh Osama was killed, to rise up and revolt to cleanse this shame,” the terror network said in a statement released by the SITE monitoring group.

Confirming bin Laden’s death for the first time, Al-Qaeda urged Pakistani Muslims “to cleanse their country from the filth of the Americans who spread corruption in it.”

In the statement posted on jihadist internet forums, the Islamist group proclaimed its Saudi-born founder a “martyr,” adding he had “terrified all the nations of disbelief.”

The White House swiftly said it was on alert for security threats as Al-Qaeda also vowed to release an audio tape made by their inspirational leader just a week before he was shot dead on Monday by US commandos in Pakistan.

“We are quite aware of the potential for activity and are highly vigilant on that matter for that reason,” said White House spokesman Jay Carney.

Intelligence seized during Monday’s operation showed the architect of the 9/11 attacks had remained closely involved in Al-Qaeda despite hiding away from the outside world.

The network had even been mulling strikes on US trains on the 10th anniversary of the September 11 attacks, US officials said Thursday.

In Abbottabad, just 50 kilometres from the capital Islamabad, where bin Laden was finally tracked down after a years-long manhunt, police marshalled a rally of about 1,000 men. Hundreds took to the streets in the insurgency-riven Pakistani city of Quetta near the Afghan border to chant “Long live Osama” and call for holy war against America.

Islamists also rallied in Cairo, but were stopped by soldiers about a block from the US embassy, and resorted to shouting “leave, leave” and “lower the (American) flag.”