Category: News; Radio 4
The BBC has been told by a well placed source that the leader of the London bombers, Mohammed Siddique Khan, featured in a surveillance operation carried out by the intelligence services last year.
According to the source, he was secretly filmed and recorded speaking to a UK-based terrorist suspect who we cannot name for legal reasons.
There is no independent corroboration for this and the Metropolitan Police declined to comment.
But if our source is correct, it would amount to a serious failure of intelligence in the run-up to the London attacks on 7 July.
In the days after the London bombings, unsourced reports suggested that Siddique Khan's name had been linked to the periphery of a UK terrorist investigation through the loosest of connections involving telephone records.
This new information, if true, shows the intelligence services had him well in their sights but allowed him to slip away.
Until now, it has been thought that Siddique Khan's plans remained secret because he and the other bombers were so called clean-skins - people with no track record in terrorism and no intelligence traces.
But a joint BBC Radio File on 4 and BBC TWO Newsnight investigation suggests Siddique Khan was in contact with Al Qaeda activists over the past five years.
A detainee held in Indonesia in connection with the 2002 Bali bombings has alleged that Siddique Khan travelled to Malaysia and the Philippines in 2001 to meet with the notorious terrorist leader Hambali.
The BBC has interviewed an academic researcher, Dr Rohan Gunaratna, who spoke to the detainee after the London bombings.
The detainee has said he took Mohammed Siddique Khan to meet and train with leaders from the extremist Islamist group Jemaah Islamiah which is linked to Al Qaeda in the Far East.
The BBC has also learned that Saddique Khan travelled to Pakistan in 2003 where he met an Islamic extremist who has since admitted to being a fixer for Al Qaeda.
We cannot name this man for legal reasons, but we can say he is a United States citizen from a Pakistani family from New York who travelled to Pakistan immediately after the 9/11 attacks.
We understand that Siddique Khan was also seen with this man in Leeds in 2003.
Siddique Khan was running a strong cover with his work as a caring teaching assistant in Leeds.
But a careful study of his background and contacts reveal a number of clues to his extremism which the British intelligence agencies apparently missed.
Notes to Editors
If using this material please credit a joint File on 4/Newsnight investigation; 8.00pm, Radio 4; 10.30pm, BBC TWO; Tuesday 25 October.
Newsnight is BBC TWO's flagship current affairs programme.
On air since 1980 its role is to be thought-provoking and informative, analysing complex issues in-depth with high quality and hard hitting films.
It is watched by 6.5 million viewers a week.
File on 4 is BBC Radio 4's award winning investigative documentary series. Just under one million people listen to the programme every week.