Citing Pakistani and Middle Eastern officials speaking anonymously, the Times said Iranian authorities were giving covert support to the Islamist militants as they fight against Nato troops.

“In many cases they are being facilitated by Iranian Revolutionary Guards,” The Times quoted a senior Pakistani intelligence official as saying.

The Times said those released include Saif al-Adel, a high-ranking Egyptian al Qaeda member on the FBI's most wanted list for alleged involvement in the deadly 1998 bombings of US embassies in East Africa.

They also include Suleiman Abu Ghaith, a Kuwaiti accused of being Al-Qaeda's official spokesman at the time of the September 11, 2001 attacks, and Abu Khayr al-Masri, a key aide to al Qaeda deputy leader Ayman Al-Zawahiri.

Three members of the family of al Qaeda leader Osama bin Laden were also among those freed, the officials were quoted by the Times as saying.

Several top al Qaeda leaders fled to Iran when the US invaded Afghanistan after 9/11 and Iran is suspected of keeping them under house arrest as a strategic asset against the United States.

Al Qaeda's top leadership including Bin Laden and Zawahiri are believed to be in Pakistan's tribal areas bordering Afghanistan, but a blitz of CIA drone strikes has taken a major toll on the group.

The Times quoted Pakistani officials as saying that Al-Adel had been named al Qaeda's chief of operations for Afghanistan and Pakistan.

In July, Bin Laden's son Omar said that 20 members of the al Qaeda chief's family were stranded in Iran as Tehran was refusing to discuss their fate with Saudi Arabia.

However a Kuwaiti newspaper reported in November that a number of leading al Qaeda members, including Abu Ghaith, had moved from Iran to Yemen. – AFP