London confidential

I've been determined to investigate 2012's efforts to stop people talking about the details of the Olympic project since I was told last year that new staff at London 2012 were required to sign confidentiality agreements.

I wondered why a project with so much public money going into it - £9.3bn - needed to be so secretive.

Now I have learned that companies building the facilities in east London are being forced to sign draconian gagging orders to keep quiet about the details of the project. Facing constant controversy about the cost of the Games, Olympic bosses are making companies sign unusually severe "confidentiality undertakings" which restrict them from talking publicly about all details of the work for six years.

I've seen copies of the contracts which even give the Olympic Delivery Authority (ODA) the right to search a company's premises and e-mails for evidence if they suspect that an employee has passed on information to the media or another third party.

The companies I have talked to are shocked that they have to sign a document which effectively allows 2012 to walk into their premises and start searching them. Legal experts have told me these contracts are draconian. You can read more about my investigation in the BBC News story, including the response from the ODA.

When I went to Beijing with the Olympics Minister Tessa Jowell in November 2007, I listened to her telling the Chinese about the importance of freedom of speech around their Games last summer. But it appears there are serious efforts being made to prevent people from talking publicly about our Olympics - unless 2012 want them to. One leading human rights lawyer has also told me that there are concerns about freedom of speech and human rights in the UK's Olympic Act which gives special powers to the Government regarding the organisation of the Games. Organisers of the 2010 Vancouver Winter Olympics have told me they have no gagging orders in place ahead of their Games. So why have we?

Adrian Warner is BBC London's Olympics correspondent.