Al-Qaeda has confirmed the death of its leader Osama bin Laden, according to a US-based jihadist monitoring service.
Five days after US president Barack Obama announced bin Laden's death in a raid by US special forces on a compound in Abbottabad, north of the Pakistan capital Islamabad, al-Qaeda vowed not to deviate from the path of armed struggle.
The group said bin Laden's blood "is more precious to us and to every Muslim than to be wasted in vain".
"It (bin Laden's blood) will remain, with permission from Allah the Almighty, a curse that chases the Americans and their agents, and goes after them inside and outside their countries," the militant network said in a statement released on Islamist internet forums and translated by the SITE monitoring service.
"Their happiness will turn into sorrow, and their blood will be mixed with their tears,” the statement. "We call upon our Muslim people in Pakistan, on whose land Sheikh Osama was killed, to rise up and revolt to cleanse this shame that has been attached to them by a clique of traitors and thieves ... and in general to cleanse their country from the filth of the Americans who spread corruption in it."
The group also said it will soon release an audio recording of bin Laden made a week before his death.
The White House said the US government remains "highly vigilant" of any attempt by al-Qaeda to revenge the killing.
White House press secretary Jay Carney said al-Qaeda's call for revenge showed it acknowledged bin Laden was dead, which had been a factor in President Barack Obama deciding not to release pictures of his corpse. Mr Obama was also concerned the gruesome images might be used to fan violence against Americans.
"We will remain extremely vigilant," Mr Carney told reporters flying with Mr Obama aboard Air Force One. "We're quite aware of the potential for activity and are highly vigilant on that matter for that reason."
Meanwhile, reports in the US claim new information shows bin Laden was planning a new attack on US targets. After killing bin Laden and four of his associates, US troops confiscated computers, DVDs and documents from the home where it is believed the al-Qaeda chief had been hiding for up to six years. These reportedly show he was plotting attacks on the US railway system.
In a separate development, it emerged overnight that extensive surveillance of bin Laden's hideout from a nearby CIA safe house in Abbottabad led to his killing. The revelation is likely to further embarrass Pakistan's spy agency and strain ties between the two countries.
The Washington Post said the safe house was the base for intelligence gathering that began after bin Laden's compound was discovered last August. "The CIA's job was to find and fix," the Post quoted one US official as saying, using special forces terminology for locating a target. "The intelligence work was as complete as it was going to be, and it was the military's turn to finish the target."
US officials told the New York Times that intelligence gathered from computer files and documents seized at his compound showed bin Laden had been orchestrating al-Qaeda attacks from the Pakistani town for years, and may have been planning a strike on the US rail sector this year, the 10th anniversary of the September 11th, 2001 attacks.
According to a document seen by the Associated Press news agency, information about the apparent plans was contained in a joint FBI and Homeland Security bulletin, which suggested al-Qaeda was considering plans to attack the US on the 10th anniversary of the 9/11 attacks.
One idea outlined in handwritten notes was to tamper with an unspecified US rail track so that a train would fall off the track at a valley or a bridge, according to the joint bulletin circulated to law enforcement officials around the country yesterday.
The al-Qaeda planners noted that if they attacked a train by tilting it, the plan would only succeed once because the tilting would be spotted the next time.
The FBI and Homeland Security told local officials to be on the lookout for clips or spikes missing from train tracks, packages left on or near the tracks and other indications that a train could be vulnerable.
Meanwhile, one of Osama bin Laden's wives has reportedly told Pakistani interrogators the al-Qaeda leader and his family had been living for five years in the compound where he was killed by US forces this week.
A Pakistani security official, who identified the woman as Amal Ahmed Abdulfattah, the youngest of bin Laden's three wives, said she was wounded in the US raid on Monday. Both Pakistan's army and its powerful spy agency, Inter-Services Intelligence (ISI), have been facing mounting pressure to explain how it was possible for bin Laden to live deep inside Pakistan undetected for years.
Elsewhere, Taliban fighters, appearing in a video purporting to show frontline militants in southern Afghanistan, have said the killing of bin Laden will inspire them to continue fighting until all foreign troops have left the country.
Agencies