Traditionalist clerics in Iran are blocking the extradition of senior al-Qa'eda members, including one of Osama bin Laden's sons, amid growing evidence that they are masterminding terrorism in other countries.
Western and Arab intelligence sources quoted in The Washington Post said up to 400 al-Qa'eda terrorists were being sheltered in eastern Iran close to the Afghan border by an elite religious militia, the Jerusalem Force.
The group is reported to be closely tied to Iranian mullahs who are contemptuous of the reformist government in Teheran.
The terrorist group is said to be headed by Saad bin Laden, 24, a son of Osama bin Laden. The report links him to suicide attacks in the Saudi capital, Riyadh, which killed 26 people and explosions in Casablanca, Morocco, which killed 32. The attacks happened within days in May.
Saad, the third eldest of Osama bin Laden's 22 children, is said to have made a telephone call from Iran to a member of the Riyadh cell days before the bombings.
Saad is reported to have grown up at his father's side in Afghanistan during the anti-Russian war of the 1980s.
He is fluent in English and is computer-literate and the Post reported that he is winning his growing terrorist role through ability rather than favouritism.
Iran has admitted that it is holding a number of al-Qa'eda members but has refused to disclose their names, arguing that it was difficult to identify them. Saudi Arabia and Kuwait are negotiating to have some of them extradited.
The Teheran government has dismissed suggestions that it is harbouring active al-Qa'eda members and has challenged foreign intelligence services to provide evidence.
It is understood that Iran's hardline clerics hope to use the captives as bargaining chips in negotiations with America over Teheran's attempts to become an independent nuclear power.
An Iranian opposition group that has exposed some of Iran's most secret nuclear sites claimed yesterday that the regime was hiding another uranium enrichment facility in Isfahan.
The National Council for the Resistance in Iran said the regime had built a site "to test centrifuges that enrich uranium" in a complex with several other known nuclear facilities.