* In urgent hearing, judge sends Qatada back to jail
* Appeal hearing over deportation due on Monday
* Cleric wanted in Jordan on terror charges (Updates after urgent bail hearing)
LONDON, March 9 (Reuters) - A British judge sent radical Muslim cleric Abu Qatada back to jail on Saturday for breaching his bail terms, two days before the government begins an appeal against a court decision blocking his deportation to Jordan.
Accused by the British authorities of posing a security risk and providing spiritual inspiration for one of the 9/11 hijackers, Qatada is wanted in his native Jordan to face terrorism charges.
Successive British governments have tried for years to get rid of the cleric, who has been in and out of jail since first being arrested in 2001. He has been living at a house in London under tight bail conditions including a 16-hour curfew.
He was arrested on Friday for breaching his bail terms, and on Saturday the Special Immigration Appeals Commission (SIAC)dealing with his case held an urgent telephone hearing into the matter.
After that hearing, Judge Stephen Irwin issued an order revoking Qatada's bail and ordering him to be detained first by London's Metropolitan Police and later at Belmarsh Prison.
The judge set a hearing for March 21 to further consider Qatada's bail.
The judge's order said that evidence suggested Qatada had breached bail conditions prohibiting him from allowing mobile phones to be switched on in his house while he is present and from allowing communications equipment such as re-writable CDs to be brought into his house.
In the latest of a series of legal blocks to the cleric's deportation, denounced by Home Secretary Theresa May, SIAC ruled in his favour in November last year. Qatada says a trial in Jordan might be skewed by evidence obtained using torture.
"I am pleased to say (Qatada) is now going to be re-detained following the hearing at SIAC this afternoon," May said during a speech to a political conference shortly after the judge's ruling, to cheers from the audience.
May's appeal against the November SIAC decision is scheduled to be heard in the Court of Appeal on Monday.
There was no connection between Qatada's arrest and the looming appeal. The Court of Appeal will consider the issue of whether Qatada would get a fair trial in Jordan, not the issue of his bail.
The Sun newspaper, which first reported news of Qatada's arrest, said counter-terrorism police had searched his north London home for 12 hours on Thursday.
A police spokesman said searches had taken place on Thursday "in connection with ongoing inquiries by the counter-terrorism command", adding that no hazardous materials had been recovered.
The cleric, a Jordanian of Palestinian origin, was once described by a Spanish judge as "Osama bin Laden's right-hand man in Europe".
Britain says videos of his sermons influenced Mohammed Atta, ringleader of the Sept. 11 attacks on New York and Washington in 2001.
Under a deal struck in 2005, Jordan has given Britain diplomatic assurances about his treatment and guarantees that court hearings would be fair.
Jordan convicted Qatada in his absence of encouraging militants there who planned bomb attacks in 1999 and 2000. Under the 2005 deal, however, he will have a retrial if he is eventually returned to Jordan. (Reporting by Estelle Shirbon; Editing by Rosalind Russell)