Conspiracy theorist: Nicholas Kollerstrom, who believes 7/7 was a set-up by the intelligence services, was interviewed for a BBC programme

The BBC was under attack last night for paying expenses to a disgraced academic who says the 7/7 London bombings may have been an intelligence agency conspiracy.

Families of victims denounced the move as appalling.

As part of his 'research', Nicholas Kollerstrom rang one father to discuss whether his daughter's body had been planted at the site of the Tavistock Square bus bombing.

Dr Kollerstrom, 61, who also denies the Holocaust, is due to appear in a programme in the BBC's Conspiracy Files series.

His theory is that the Al-Qaeda inspired bombers were 'innocent patsies', set up by elements of the Israeli, British and U.S. security agencies.

The BBC has admitted paying Dr Kollerstrom expenses, including the fare from London to Luton, where bombers Mohammed Sidique Khan, Shehzad Tanweer, Jermaine Lindsay and Hasib Hussain caught a train to King's Cross before the 2005 attacks which killed 52 innocent people.

The corporation's move has astonished the families of those who died or were injured.

'For the BBC to actually fund somebody like this is totally disgraceful,' said John Taylor, whose 24-year- old daughter Carrie was one of seven killed by Tanweer. 'He is helping the terrorists more than anything and I am not happy with the BBC giving him a platform.'

Sean Cassidy, whose son Ciaran, 22, died in the Russell Square blast, said: 'It is appalling. The families are aware of this man and are trying to avoid him. He has caused a lot of upset.'

The scene at Tavistock Square after the bus exploded. Mr Kollestrom believes the bombing was a conspiracy

Last month Dr Kollerstorm, an astronomer and historian, was stripped of an honorary research fellowship at University College London after it emerged he had written a paper entitled The Auschwitz 'Gas Chamber' Illusion on a Far-Right website.

He claimed the Nazi concentration camp was like a holiday complex where inmates could sunbathe beside a swimming pool and watch water polo matches.

The BBC defended its use of Dr Kollerstrom and stressed it only paid expenses such as the £8 train fare to Luton, where he filmed an interview for the programme.

A spokesman said: 'The Conspiracy Files series investigates whether there is any truth to the many conspiracy theories which have grown up around terrorist attacks.

'Nick Kollerstrom has advanced a number of theories which will be investigated in detail by the BBC. His view of the Holocaust will be scrutinised in the programme. He has not been paid by the BBC.'

Dr Kollerstrom admitted phoning the family of one victim but said he had not wished to cause offence. He said he was researching 'anomalies' highlighted in a newspaper article which suggested the father believed his daughter's body had been planted.

He added: 'The last thing I want to do is cause grief to a family. But they did go public and I thought they wouldn't mind someone querying them about public statements they made.'