The former imam of Finsbury Park Mosque expressed an interest in buying Jameah Islameah, near Crowborough, East Sussex, in the late 1990s.

When his offer for the 100-room building and its 54-acre grounds was rebuffed, Abu Hamza tried to acquire control of an isolated ranch in the US. According to a federal indictment, he hoped to turn into a jihad training camp.

Followers of Abu Hamza, including Abu Abdullah, a close aide, are among 14 men being questioned by police about alleged extremist activities during camping weekends in the grounds. It is suspected that the group’s ringleaders were trying to indoctrinate young British Muslims in order to build a terrorist cell. Scotland Yard has obtained warrants for extra time to question the suspects, who were arrested on suspicion of the preparation, commission or instigation of terrorism.

The Charity Commission announced yesterday that it was examining the activities of the school, which registered as a charity in 1994, under the title Jameatul-Uloum-al-Islameyah.

The school was already causing concern after a highly critical Ofsted report and because its annual accounts were several months overdue.

The charity watchdog said: “The commission is in touch with the relevant law enforcement agencies following the recent police action in searching the charity’s premises. We are in touch with the charity’s trustees with regard to a meeting to discuss the police action and other matters concerning the administration of the charity.

“Any breach of the criminal law is primarily a matter for the law enforcement agencies . . . we will remain in close touch with those agencies while the police investigation continues.”

A former aide to Abu Hamza said that the cleric visited the school at least five times in the late 1990s, taking followers to camp in the grounds, which include woodland and a lake. The school was built in 1868 as a Roman Catholic seminary, and became a ballet school.

It was bought in 1993 by four men on behalf of the Jameatul-Uloum-al-Islameyah. Land Registry records do not show how much they paid.

Abu Hamza, who studied civil engineering in Brighton, knew the area before organising camps there. He approached London-based Egyptian businessmen to raise funds to buy the building. The trustees of the school are understood to have been suspicious of him and to have rejected his approach.

He then considered acquiring land in Wales and Lancashire to establish his base, before one of his followers raised the possibility of taking over the ranch in Bly, Oregon.

Abu Hamza sent two aides to the US in 1999 to run a camp at the ranch and allegedly to evaluate it as a jihad training facility. His involvement with the project led to his being charged in the US with attempting to set up a terrorist camp.

The cleric faces extradition to the US to face a series of terrorist charges after the completion of his appeal against his convictions in Britain for inciting murder and race hatred.

A British Muslim leader said he found it hard to believe that the school was linked to extremism. Imam Abduljalil Sajid, of the UK Muslim Council for Religious and Racial Harmony, told the BBC that Balil Patel, one of the school’s owners, was not a man “who has anything to do with extremism or violence. He would oppose violence and terror and co-operate with the authorities 100 per cent.”

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