A British Muslim was convicted yesterday of being a member of al Qaeda and directing a terrorist organisation in Britain, the first conviction of its kind in the United Kingdom, police said.

Rangzieb Ahmed, 33, was found guilty by a jury at Manchester Crown Court of belonging to the group led by Osama bin Laden and of leading a three-man terrorist cell engaged in the plotting of an attack, possibly overseas. His co-defendant Habib Ahmed, 29, who is not related, was also found guilty of belonging to al Qaeda. The two will be sentenced today.

"Rangzieb Ahmed is a very dangerous man," Manchester police said in a statement following the verdicts.

"He consorts with senior terrorist figures and has devoted his life to creating and working with terrorist networks. We believe that he was intent on masterminding terrorist attacks and would have considered mass murder part of his duty."

Prosecutors presented evidence showing Rangzieb Ahmed had close contact with senior members of al Qaeda, including Hamza Rabia, a man suspected of having been a deputy to bin Laden.

Habib Ahmed, a taxi driver, was arrested after he was found in possession of two diaries which contained details, written in invisible ink, of top al Qaeda operatives, including Rabia.

The diaries, which belonged to Rangzieb Ahmed, were described in court as a "terrorist's contact book".

"There is no doubt Rangzieb Ahmed was at the centre of the Qaeda web, and was using his position to manipulate people, drawing them in too," the police said.

"We don't know where Rangzieb's next target would have been, or what exactly he was working towards, but we are sure he was attack-planning."