Minh Quang Pham, 29, who is of Vietnamese origin, was detained by Scotland Yard officers last week on an extradition warrant from the America, where he faces a minimum sentence of 40 years’ imprisonment if he is convicted of all the charges against him.

Also known as Amin, he is accused of travelling to Yemen in December 2010 and taking an oath of allegiance to al-Qa’ida in the Arabian Peninsula (AQAP), an offshoot of Osama Bin Laden’s organisation now regarded by western intelligence as the most threatening splinter group of the Islamist extremist movement.

In the latest example of British and American counter-terrorism agencies tracking alleged “clean skins”, suspected terrorists without previous known links to extremist groups, Mr Pham is understood to have been held in immigration detention prior to his formal arrest last Friday. The Yard declined to comment on his nationality or where in Britain he was arrested.

An indictment filed on behalf of the FBI claims that Mr Pham, a computer expert who had been living in the New Cross area of south London, spent six months in Yemen receiving weapons training and providing “expert advice and assistance in photography and graphic design of media” for AQAP.

Janice Fedarcyk, assistant director of the FBI’s New York office, said: “The defendant not only allegedly pledged an oath to al-Qa’ida in the Arabian Peninsula, and received military training from AQAP. He also helped design and disseminate its propaganda.”

It is unclear whether Mr Pham is being accused of direct involvement in the creation of Inspire, a highly-polished online English language magazine which mixes Koranic analysis and jihadist propaganda with descriptions of how make a homemade bomb and tips on encryption.

Sources close to the US investigation said Mr Pham, who is being held at a top security unit in south London’s Belmarsh Prison, is alleged to have met numerous senior AQAP figures including the group’s then leader, Anwar al-Awlaki, who is thought to have come up with the idea of Inspire, and the magazine’s editor, Samir Khan.

The men, who were both American citizens, were killed in a CIA drone strike last year after a series of attacks and spectacular near-misses associated with AQAP, including the plot to smuggle a bomb concealed in underwear onto an airliner that was disrupted by a British agent this May.

Al-Awlaki, whose group was also behind two bombs hidden in photocopier toner cartridges intercepted in Britain and Dubai in 2010, preached via the internet and influenced a string of so-called “lone wolf” terrorists, including Major Nidal Hasan, the American army officer who murdered 13 people on a Texas military base, and Roshonara Choudry, the student who stabbed Labour MP Stephen Timms in his east London surgery.

Inspire, which is now in its ninth issue and promotes itself as “the first magazine to be issued by the al-Qa’ida organisation in the English language”, is part of a wider strategy by AQAP to promulgate its doctrine and influence single attackers rather than rely on conventional terrorist cells.

Material published includes an article entitled “Make a Bomb in the Kitchen of Your Mom” and an illustrated guide on how to handle and fire a handgun and other weapons.

According to the American authorities, Mr Pham was engaged in a range of activities while in Yemen and was spotted toting a Kalashnikov rifle in March or April last year. The indictment claims that the Londoner and others provided AQAP with “personnel, property, services, facilities, communications equipment, expert advice and assistance, training and weapons”.

Mr Pham was arrested last July at Heathrow airport after arriving from Bahrain.

In a statement, the Yard said: “Minh Quang Pham has been arrested by officers from the Metropolitan Police Service Extradition Unit. He was arrested in connection with alleged terrorism offences in the Republic of Yemen.”

http://www.independent.co.uk/news/uk/crime/alqaida-online-propaganda-expert-arrested-in-britain-7917278.html