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, 29, is a white Muslim convert who featured in a BBC documentary last year filmed by his own brother about his conversion.
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”.