Mr Aswat, 30, who grew up in the same area in west Yorkshire as suicide bomber Mohammad Sidique Khan, is alleged by US authorities to have been involved in setting up a terrorist training camp in Oregon.
The arrest of Mr Aswat, apparently last week, came after he was said to have been tracked by US agents from South Africa. The Foreign Office has denied reports that a US request to hold him in the UK a week before the 7 July blasts had been turned down.
Officials also said that it was unclear whether the US authorities had a valid arrest warrant for Mr Aswat. The indication from Washington was that there might be a "sealed" warrant in his name after a grand jury indictment.
British security sources stressed yesterday that although there was "interest" in talking to Mr Aswat, he was not the "mastermind" of the London attacks. It was also untrue, they said, that he had come to Britain to organise the bombings, leaving just a few days before 7 July.
There was widespread reporting in some British newspapers, allegedly supported by "members of the Pakistani intelligence", that Mr Aswat was arrested in Pakistan with £13,000 and a belt of explosives. That, however, was untrue.
It is believed, instead, that Mr Aswat had been in South Africa for some time.Reuse content