Al-Qaeda leader Osama Bin Laden has appeared in a video clip on a militant website, the first time he has been heard for more than a year.
Bin Laden says the Prophet Mohammed wished martyrdom
But the clip, less than a minute long, is undated and correspondents say it may be re-run footage. Its authenticity also cannot be independently verified.
Osama Bin Laden is filmed outdoors in army fatigues and praises those who die in the name of "holy war".
The US Senate on Friday voted to double the reward on him to $50m (£24.5m).
The clip of the al-Qaeda leader features in a 40-minute video on a militant web site that carries the logo of al-Qaeda's media wing.
The video mainly shows fighters paying tribute to fellow militants killed in Afghanistan.
Ayman al-Zawahiri's messages are usually more specific
Bin Laden says: "The happy [man] is the one that God has chosen to be a martyr."
He says the Prophet Mohammed "wished upon himself this status".
The last Bin Laden message - an audio tape in July 2006 - referred to identifiable events, including the situation in Somalia.
However, BBC security correspondent Frank Gardner says this time he makes no reference to recent events, unlike his strategic adviser Ayman al-Zawahiri, whose frequent videos are far more specific.
The bulk of the new video pays tribute to dead militants.
The self-proclaimed leader of al-Qaeda in Afghanistan, Mustafa Abu al-Yazeed, praises "courageous knights" who have answered the call "for the sake of God to kick out the occupier who has desecrated the pure soil of Afghanistan".
Another key figure identified on the video is Abu-Yahya al-Libbi, who escaped from US custody at the Bagram airbase in Afghanistan two years ago.
He says the Muslim world is "offering the best of its men and sacrificing the good of its sons... to protect its ideology".
On Friday, the US voted 87-1 to double the reward for the death or capture of Osama Bin Laden.
The vote came amid warnings that al-Qaeda had rebuilt its capacity to mount attacks and was trying to insert agents into the US.
A leaked draft of a new US intelligence report says al-Qaeda is at its strongest since just before the 11 September 2001 attacks on the US.