A firebrand preacher once described as "Osama bin Laden's right-hand man in Europe" has been granted bail by an immigration tribunal.

Abu Qatada, who last month defeated the government's efforts to deport him to Jordan, will be subject to a 22-hour curfew when he is released.

Home Secretary Jacqui Smith said yesterday she was "extremely disappointed" at the decision and promised "all steps necessary to protect the public". The bail decision by the Special Immigration Appeals Commission (SIAC) is a fresh blow to the government's anti-terror policies.

Now the Home Office, which is appealing against the decision to block the deportation, will seek the strictest possible conditions on the preacher once released.

Qatada has been convicted in his absence in Jordan of involvement with terror attacks in 1998.

The radical cleric once called on British Muslims to martyr themselves, and tapes of his sermons were found in a flat in Germany used by some of the September 11 hijackers.

Ms Smith said: "I am extremely disappointed the courts have granted Abu Qatada bail, albeit with very strict conditions. Public safety is our main priority and we will take all steps necessary to protect the public.

"I am not prepared to comment on details of individuals' contingency plans, but the Government's priority is to protect public safety and national security.

"I am already seeking to appeal the Court of Appeal's decision that it is not safe to deport Qatada and we will continue with deportation action with this and the other Jordanian cases."

He is currently being held in a specialist unit at Long Lartin in Worcestershire but could be released within weeks.

SIAC had originally dismissed Qatada's appeal against deportation on the grounds that Amman had signed a "memorandum of understanding" with the UK.

The so-called MOUs are designed to give reassurance that countries with poor human rights records will not torture or ill-treat anyone returned to their soil.

But the Court of Appeal concluded that because of the issue of evidence obtained by torture in Jordan, SIAC had misdirected itself in law and its decision could not stand.

Home Office minister Tom McNulty said at the time that he was confident the preacher would be deported.

Shadow Home Secretary David Davis said: "This whole situation undermines the government's assurances that memorandums of understanding are the solution to deporting terror suspects.

"The government should at last answer our calls to focus on prevention and prosecution - for example by allowing the use of intercept evidence in court - rather than just trying to deport these individuals once they are here.

"They should establish a dedicated UK Border Police to prevent foreign terror suspects from entering the country in the first place."