White Muslim convert Richard Dart and a former police community support officer were among six people arrested for allegedly plotting a terror attack in Britain.Richard Dart, who was radicalised by the cleric Anjem Choudary, was held following police raids in east and west London.
A former PCSO and two of his brothers, who were living just over a mile from the Olympic site in Stratford, were also among those detained during the police and MI5 operation to prevent a suspected terror assault.
One of the brothers was Tasered by officers. Counter-terrorism police had first searched their home last November.
The Daily Telegraph understands the police moved over fears that a group had obtained a sword which could potentially be used in a terrorist attack.
Mr Dart, 29, the son of Dorset teachers, featured in a BBC documentary last year filmed by his own brother about his conversion. During the film, called My Brother the Islamist, he was seen protesting about British soldiers in Afghanistan and accused them of being "murderers".
He also called for Sharia law to be established in Britain, as well as saying that one of his friends used to be "in the police", but is not any more. Mr Dart has changed his name to Salahuddin al Britani. Salahuddin comes from the medieval leader who drove King Richard I from Jerusalem during the Crusades.
It emerged last year that the former BBC security guard was living off state benefits in a luxury flat in Mile End, east London.
Anjem Choudary said he had converted Mr Dart but had not been in contact with him for more than a year.
The six, which included one woman, were arrested on suspicion of the commission, preparation or instigation of acts of terrorism after police raids during the early hours of Thursday, July 5.
Neighbours in Stratford said one of the brothers was Jahangir Alom, 26, who served as a former Metropolitan community support officer between May 2007 and September 2009. He is understood to also go under the name of Abu Khalid.
In 2010, Mr Khalid appeared in a YouTube video to say why he had stopped being a PCSO and had become an Islamic fundamentalist.
In the film he explains that he realized he was leading a "misguided" life after meeting with some "brothers". He said as a PCSO he was involved in stop and searches and that he now realised he was "implementing kuffur (enemies of Islam) law on the streets of London".
The other two brothers arrested are understood to be Mohammed Alomgir, 24, and Moybur Alom, 18. Mr Alomgir was hit with a police Taser during the arrests but did not require hospital treatment.
At the same time, in Ealing, west London, a 29-year-old man, believed to be Mr Dart, was arrested in the street, while a 21-year-old man and a 30-year-old woman were held at separate residential premises.
Police insisted that the arrests were not linked to the Olympics and that an attack was not believed to be imminent.
The suspects had been monitored by counter-terrorism officers and MI5 for some time and the arrests were part of a pre-planned intelligence operation.