Al-Qaeda has confirmed the death of its leader Osama Bin Laden, according to a statement attributed to the group and posted on jihadist internet forums.
The statement said his blood would not be “wasted” and that al-Qaeda would continue attacking the US and allies.
Bin Laden’s death would be a “curse” for the US and urged an uprising in Pakistan, the statement added.
The militant was shot dead on Monday when US commandos stormed his compound in the Pakistani town of Abbottabad.
The raid was carried out without the prior knowledge of the Pakistani authorities, increasing tension between the two countries.
Several rallies are being held across Pakistan on Friday in protest.
The statement published on jihadist web forums said an audiotape would be released of the al-Qaeda leader speaking a week before his death.
“[Osama 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,” it warned.
“Their happiness will turn into sorrow, and their blood will be mixed with their tears. We call upon our Muslim people in Pakistan, on whose land Sheikh Osama was killed, to rise up and revolt.”
The statement appeared on jihadist web forums
Correspondents say many Pakistanis are angry at what they see as a US infringement of their country’s sovereignty.
They are also critical of Pakistan’s government for allowing the commando operation to happen, although officials deny they were told.
Around 1,000 people gathered in central Abbottabad following Friday prayers, AFP news agency reported.
They set fire to tyres, blocked a main road and shouted “Down, down USA!” and “terrorist, terrorist, USA terrorist”.
Anti-American sentiment also appeared to be high at a similar protest in the south-western city of Quetta, the capital of Baluchistan province.
However, a BBC correspondent in Rawalpindi says the anti-US protest there was much smaller than expected with about 50 people turning up.