Secret negotiations have taken place to arrange the release from a British jail of one of al-Qaeda’s most important operatives in Europe, The Times has learnt.

The prisoner, who can be identified only as U, is expected to be released from the high-security wing at Long Lartin jail next week.

Appeal Court judges ruled in April that the man, a 45-year-old Algerian veteran of al-Qaeda’s Afghan training camps, should be freed on bail. But discussions between security agencies and U’s lawyers became deadlocked over the conditions restricting his movements and whom he can meet when he leaves prison.

The authorities are understood to have sought bail terms more stringent than the 22-hour curfew imposed on the radical cleric Abu Qatada when he was freed last week. These conditions would require U to spend all his time indoors.

Security agencies blocked requests for U to live in London claiming that he has extensive contacts among extremist Islamist groups there. They also objected to an address in Brighton. U will be required to wear an electronic tag, subjected to round-the-clock monitoring and forbidden to use the internet or a mobile phone.

When the agreement is finalised the details will be passed to a judge who can release U from the prison in Worcestershire without any further court hearing. The Home Office refused to comment on the situation beyond saying it was seeking “the strictest bail conditions” possible.

While Abu Qatada is a preacher whose role in the al-Qaeda network is to justify and encourage jihad, U is alleged to be a terrorist leader who recruited, trained and facilitated operations. Members of his group, which was formed with the personal approval of Osama bin Laden, have been convicted in the US of a plot to blow up Los Angeles International Airport in December 1999 and, in Germany, of a plan to bomb the Strasbourg Christmas market a year later.

U, a studious figure with a reputation in prison as a bookworm, arrived in Britain in 1994 and claimed asylum on the ground that he had been ill-treated in Algeria.

Between 1996 and 1999, according to the Special Immigration Appeals Commission (SIAC), he was based at al-Qaeda’s Khalden training camp in Afghanistan where he formed a cell of north African terrorists tasked with exporting jihad to the West.

He then returned to London and ran his operations out of the Finsbury Park Mosque, then under the control of Abu Hamza al-Masri, and maintained close contact with Abu Qatada.

Mr Justice Ouseley said in one SIAC ruling that U “had a wide range of extremist Islamic contacts inside and outside the United Kingdom. He was involved in a number of extremist agendas. By being in the United Kingdom he had brought cohesion to Algerian extremists based here and he had strengthened links with the terrorist training facilities in Afghanistan and Pakistan.” In February 2001, several months after the Strasbourg bomb plot was foiled, U was arrested at Heathrow airport as he tried to board a flight to Saudi Arabia with fake passports. At addresses linked to U they found fake credit cards, a telescopic rifle sight and other terrorist paraphernalia.

But rather than prosecute U in the British courts, the authorities agreed to an extradition request from the US where one of his recruits had given detailed statements implicating him in the plot to attack Los Angeles airport.

The informant, Ahmed Ressam, was to have been the key witness against U until he withdrew his statements in 2003. Two years later the US abandoned its extradition attempt but, rather than release or charge U, British authorities sought to deport him to Algeria. In a memo to Algiers in March 2006, officials wrote of U: “Senior position in Mujahidin training camp in Afghanistan. Direct links to Osama bin Laden and other senior AQ (al-Qaeda) figures. Involved in supporting terrorists including those involved in the planned attack on the Strasbourg Christmas Market in 2000, and an earlier plan to attack Los Angeles Airport.”

SIAC judges later ruled that there were “credible grounds for believing each of these assertions” and rejected his appeal against deportation.

But that decision was overturned by the Appeal Court. As with Abu Qatada, the courts ruled that if U could not be deported, there was no legitimate reason to detain him indefinitely.

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