Islamic militants in Pakistan believe the videotape showing Osama bin Laden chuckling about the September 11th attacks has been fabricated by the US.
They claim it is a US attempt to justify the war in Afghanistan. "This videotape is not authentic," said Mr Riaz Durrani, a spokesman of the Jamiat Ulema-e-Islam, which spearheaded a series of violent pro-Taliban rallies in Pakistan. "Americans made it up after failing to get any evidence against Osama".
US officials have said they hoped influential doubters in the Islamic world would be swayed by the tape.
"I don't see how any rational person could come away thinking, anywhere in the world, that Osama bin Laden had nothing to do with the 9-11 events," said Senator Mr Richard Shelby, an Alabama Republican.
But most Islamic and militant groups in Pakistan - which opposed a decision by President Gen Pervez Musharraf to side with the United States in its war against terrorism - say the tape appears to be concocted.
Mr Ameeruddin Mughal, a spokesman for the outlawed Harkat-ul Mujahedeen, an Islamic militant group fighting in Indian Kashmir, says the tape shows somebody who resembles bin Laden - not the Saudi terrorist. In the age of computers and digital technology, it's not difficult to make a fake video, he said.
The disjointed homemade videotape showed bin Laden dining with several lieutenants and an unidentified Saudi sheik. Bin Laden was shown saying in Arabic that the events of September 11th "benefited Islam greatly." Durrani says bin Laden would never express happiness over the killing of innocent people.
The British-based Islamic group Al-Muhajiroun said the tape appeared to be of bin Laden, but was taken out of context.