Al-Qaeda leader Osama bin Laden said in a video issued ahead of the sixth anniversary of the Sept 11 attacks that the United States was vulnerable despite its economic and military power.
It was not clear when the tape, acquired by Reuters Television from a web trawler in Europe, was made.
Following are some facts about bin Laden:
* Born in 1957 in Saudi Arabia, the 17th of 57 children, bin Laden made his name fighting with Arab volunteers against the Soviet Union in Afghanistan in the 1980s.
* Part of a family made rich by the Saudi oil boom, bin Laden gained a degree in civil engineering. Some reports say in his student days he could be found in flashy Beirut nightclubs, a free-spender and heavy drinker, fighting over dancers and bar girls.
* How he got embroiled in radical Islamic politics is unclear, though the late 1979 Soviet invasion of Afghanistan appears key.
* Established al Qaeda, Arabic for "The Base", in 1998. The group is a magnet for radical Muslims seeking more fundamentalist governments in their home countries and with a common hatred of the United States, Israel and moderate Muslim governments.
* With his family fortune, bin Laden used Afghanistan to set up training camps and as a base from which to plan attacks on Western countries.
* Besides Sept. 11, Washington has also linked bin Laden to a string of attacks - including the 1998 bombings of American embassies in Kenya and Tanzania and the 2000 bombing of the warship USS Cole in Yemen.
* Has evaded a massive manhunt since late 2001 when U.S.-led forces overthrew the Taliban, which was harbouring him in Afghanistan. He is believed to be hiding in border areas between that country and Pakistan.
* Before the tape released on Friday, Bin Laden was last seen in a video statement on the eve of the Nov. 2004 U.S. presidential election. Since then, he has issued several new audio messages, the last in July 2006 when he vowed al Qaeda would fight the United States across the world.
* Mullah Dadullah, a senior Taliban commander told Al Jazeera in April 2007 that bin Laden is orchestrating militants' operations in Iraq and Afghanistan. He also said that he had ordered the attack on Feb. 27, 2007 at the U.S. Bagram base during a visit by US Vice President Dick Cheney to Afghanistan.
* Washington has wanted him dead or alive and last July, the U.S. Senate voted to double the bounty on him to $50 million and it also required US President George W. Bush to refocus on capturing him after reports that al Qaeda is gaining strength.