Arabic TV channel Al-Jazeera has broadcast what it says is unseen footage of Osama Bin Laden meeting some of the 9/11 hijackers.
The channel said it showed al-Qaeda leaders "preparing for the attacks and practising their execution".
Bin Laden is seen walking outdoors in a mountainous area wearing a dark robe and white head gear.
The broadcast came four days before the fifth anniversary of the 11 September 2001 attacks.
The footage also shows the al-Qaeda leader meeting senior figures Ramzi Binalshibh and Mohammed Atef in what al-Jazeera said were the mountains of Afghanistan.
Binalshibh was captured in 2002 and Atef was killed by a US air strike in Afghanistan in late 2001.
The tape also showed al-Qaeda training exercises
The BBC's Adam Brookes in Washington says it appears to be a meeting held just a few days before the 9/11 attacks took place.
He says that although there will be little current intelligence to be gleaned from the videotape, the images and their ghostly quality serve as reminders of the intricacy and potency of the 9/11 plot.
Al-Jazeera also showed a tape said to be of the new al-Qaeda leader in Iraq urging Iraqis to join with insurgents.
The speaker on the tape, identified as Abu Hamza al-Muhajir, says he is confident victory will be achieved.
Muhajir is said to have taken over al-Qaeda in Iraq after the killing of Abu Musab al-Zarqawi in June.
Muhajir tells US forces not to be "proud of the number and the equipment", adding: "The war has just begun."
Al-Jazeera also showed "suicide" videos by Wael al-Shihri and Hamza al-Ghamdi, two of the hijackers who crashed planes into the World Trade Center.
The station did not say how it obtained the videos.