In a letter to the BBC, he accused the documentary's maker John Sweeney of expressing his 'personal prejudices, bigotry and animosity' and harbouring 'hatred against my religion'.

Scientologists have been following the makers of the documentairy and have produced their own programme which is being distributed on 100,000 DVDs being sent to MPs, civil servants, religious groups, media organisations and business leaders.

The DVD features footage of John Sweeney shouting at a Scientologist after complaining of feeling 'brain-washed' by an anti-psychiatry exhibition created by the group.

Having been followed by Scientologists for six days, one accused Sweeney of giving a Scientology critic an easy ride even though he'd only heard part of the interview.

At this point, Sweeney shouted: 'You were not there at the beginning of the interview! You were not there! You did not hear or record all the interview!'

A BBC inquiry found no misconduct by Sweeney, yet Scientologists have posted the clip to YouTube and are attempting to make capital from the fact that Sweeney 'lost it'.

Sweeney has apologised and attempted to justify his behaviour.

"I am hugely embarrassed," he said.

"I look like an exploding tomato and shout like a jet engine and every time I see it it makes me cringe. The moment it happened I said sorry. I let the side down and the BBC down and I am ashamed. But I felt I was being brainwashed and if people see the full clip I think they will have more sympathy with me."