John Wadham talks exclusively to BBC News online about why the information should be published on the Internet

John Wadham - who is also general secretary of civil rights group Liberty - also called for better international regulation of the Internet.

Mr Wadham was speaking hours after his client David Shayler was arrested in Paris.

Mr Shayler left Britain last year after revealing details about the service to a Sunday newspaper, and was living in exile.

Letter litter claim

Last week it was revealed that the government had attempted to stop him revealing further allegations on his Website.

Lawyer John Wadham is also a leading Liberty campaigner

Mr Shayler's Internet Service Provider in the US was warned that reproducing information would breach an injunction.

But Mr Wadham says because of the First Amendment of the US Constitution, lawyers acting for the company probably advised the firm to "put the government's letter in the bin".

He said: "Injunctions relating to issues of parochial national security and the Official Secrets Act, probably won't cut any real ice with other people in other countries."

Mr Wadham said negotiations with the government had been going on for six months to ensure that any disclosures made did not damage UK national security

"Issues of freedom of expression and the right to information are now worldwide issues and there needs to be proper worldwide regulation to protect those fundamental rights and also protect national security.

"At the moment we have a mish mash of rules which apply to one country and not another."

More in the future? David Shayler's current Website

He hoped that the case would help resolve the balance between security and freedom on the Net.

Mr Wadham said he had not been able to speak to Mr Shayler since his arrest so did not know whether he still planned to publish any further revelations on his homepage.

As he spoke, all the page in question showed was a picture of a pocket watch and the message: "Welcome to the Future Website of shayler.com."

Government accused of hypocrisy

MI5's coat of arms reflects its military heritage

The Sunday Times newspaper says Mr Shayler was in Paris meeting Richard Tomlinson, an MI6 agent who served a year in jail for handing over secret information to an Australian publisher when seeking a book deal.

Mr Tomlinson has also been questioned by French police.

The arrest on Saturday night came before a scheduled appearance on Sunday morning's Breakfast with Frost programme on BBC One.

Mr Wadham, who briefed the Labour party on security matters when they were in opposition, stood in for his client.

Attorney General John Morris is accused of hypocrisy

The Attorney General John Morris is seeking Mr Shayler's extradition to face charges under the Official Secrets Act, but Mr Wadham said he would fight any such move.

He said the Attorney General, a government minister, was acting hypocritically as he had opposed the act while in opposition, when Mr Wadham remembered Labour saying it was "too draconian".

He said he could not discuss the details of the case but that the information was in the public interest.

The act makes it illegal to reveal anything about the workings of the intelligence agencies, even if the disclosures were made in the public interest.

Mr Wadham also denied that Mr Shayler has no evidence for his claims, and blamed bureaucracy and the failure of different government departments to communicate for the arrest, which had come as a surprise.

'Nobody twisted his arm'

The spy novelist Frederick Forsyth told the programme he had no sympathy for the former agent.

MI5 HQ: The home of the organisation in London

"Nobody twisted his arm. Nobody put a gun to his head and said you've got to become a member of MI5.

"He signed a contract, he broke it. He swore an oath, he broke it. He knew the parameters of the Official Secrets Act, he decided to break it."

Mr Shayler's girlfriend Annie Machon also appeared on the programme to express her anger, and complain that she had not been allowed to speak to her partner, or even find out where he was being held.