Mystery deepens over 'Bin Laden's ambassador'

Britain's most wanted man, Abu Qatada, is now in Belmarsh prison in south-east London. But the arrest last week of the man described as Osama bin Laden's "ambassador" in western Europe has simply deepened the mystery surrounding his whereabouts for the past 10 months.

Senior associates of the radical 42-year-old Muslim cleric maintain the official line that he was on the run until the police and MI5 swooped on a council flat in Elephant and Castle, south London, on Wednesday. But at least one foreign intelligence agency has openly claimed that the British authorities knew where he was all the time.

The importance of Abu Qatada, also known as Sheikh Abu Omar Mahmood Abu Omar, is not in doubt. Spain's chief anti-terrorist investigator, Judge Baltasar Garzon, has called him "the spiritual head" of Islamist militants in Europe. Jordan has convicted him in his absence of plots against American and Israeli tourist targets. The "shoe bomber", Richard Reid, who proclaimed his al-Qa'ida membership in a US court; the "20th hijacker", Zacarias Moussaoui, also in custody in the US; Djamel Beghal, accused of being Osama bin Laden's main recruiter in Europe – all are linked to him.

On the face of it, his arrest was a coup for the British authorities. According to Sheikh Omar Bakhri Mohammed, UK leader of Al-Muhajiroun, an organisation which seeks to promote the rule of Islamic law, Abu Qatada had spent most of the past 10 months closeted in the Elephant and Castle council flat, alone save for the occasional visit by "someone" who supplied him with basic provisions like food and water. He spent much of his time in an internet "chat room" called Paltalk, venturing outdoors briefly only once or twice, using an alias.

His cover was blown, insisted Mr Bakhri, only when his wife accidentally switched on her mobile phone while visiting her husband last week. "A mistake was made last Wednesday," he said. "His wife went to visit him for a few days. While she was visiting, her mobile phone was off, but somehow she put it on. The police picked up the signal straight away, and raided the flat immediately."

Others, however, have questioned the picture of a hunted man living for months on end within walking distance of Downing Street and the Houses of Parliament, let alone the headquarters of the agencies seeking him. The French secret service told Time magazine in July that Abu Qatada was an informer who was living in the north of England under the protection of British intelligence, a claim strongly denied at the time. Last week a British source said persistent allegations of this nature all came from one ill-disposed French official.

Some Islamist radicals also believe Abu Qatada was an informer. He may have been associated with militant cells from Italy to Spain and Germany, as well as individuals such as Reid, who like Moussaoui and Beghal attended his weekly prayer meetings at the Four Feathers social club in central London. But his opponents point out that scores of activists who met him have been arrested, and many terror plots in Europe have been foiled in recent months.

Some allege the cleric was allowed to remain at large as long as he severed all contact with his former associates. According to this theory, he was arrested after violating the agreement. At a recent meeting of hardline Islamists in London, an email purportedly from Abu Qatada was read out, praising Afghanistan's extreme Taliban movement and saying: "The time of victory is near. All over the world Muslims are sacrificing more and contributing more to the struggle ... May Allah accept us all to be martyred."

But if the British intelligence agencies can be absolved of collusion with Abu Qatada, they may not be able to escape the charge of inefficiency. The Bethlehem-born cleric came to Britain as a political refugee in 1993, and lived on state benefits in Acton, west London, where he quickly became known for his uncompromising rhetoric. He denied involvement in the September 2001 attacks but refused to condemn them.

The US, however, put him on a list of "specially designated global terrorist individuals", while the Treasury froze his assets, reportedly including a bank account with £180,000 in it (he denied the reports). "I do not belong to any group or any organisation whether terrorist or jihadi ..." he said. "I'm a Muslim who believes in Islam. I believe in jihad and I believe in the necessity of liberating our nation and freeing it from bondage."

Despite all this, Abu Qatada disappeared in December, hours before legislation was passed under which he would have been taken into indefinite detention – the legislation, indeed, under which he and 10 others are now being held in Belmarsh. As neighbours watched, he loaded up his people carrier with his wife and their four children and drove off.

Wherever he has been and whatever he has been doing since, the British authorities now have to decide what to do with the cleric. Do they keep him under wraps for years to come, hand him over to one of the many countries demanding him, or seek to put him on trial here? And if he is ever heard from, what will he have to say?