Former spy faces court battle to publish book

The Government has launched a legal battle to stop a former MI5 undercover agent publishing a book on the inner workings of the secret service.

The book is understood to be a detailed exposé of the operational successes, failures and recruiting techniques of the covert organisation.

The agent, a former member of the special forces, successfully penetrated the IRA, organised crime gangs and more recently recruited agents to infiltrate jihadist groups plotting terror attacks in Britain.

The government gagging order has overtones of the Spycatcher scandal in 1987, when Peter Wright, another former MI5 agent, tried to publish details of his work to uncover a traitor within the security service.

Attempts to ban Spycatcher, which was eventually published in Britain and sold more than two million copies, ensured its notoriety and helped to earn Mr Wright more than £1 million.

Legal proceedings against the MI5 agent, whose 300-page manuscript is being targeted by the Government, are due to begin at the High Court in London this week. A senior judge has been appointed to hear the case, which will be held in secret. He will rule on whether publication of the book would breach national security. Such are the stakes surrounding the outcome that the loser is likely to appeal immediately against the judge's ruling.

All MI5 employees must now sign legally binding confidentiality clauses in which they agree not to publicise any of the agency's activities. But it is unclear whether the author of Siberia, the code word the agent used to signal that his life was in extreme danger, actually signed a confidentiality document.

The Sunday Telegraph understands that the book reveals how the agent, who has been decorated by the Queen for bravery, was recruited and trained to develop multiple personalities which he used to penetrate criminal and terrorist networks for more than 15 years. It also focuses on the highs and lows of his career and how he eventually developed post-traumatic stress disorder after spending years working undercover in dangerous situations.

The MI5 department which deals with undercover agents is one of the most secret within the organisation. Of the 3,000 employees working for the security service, only a handful are ever chosen for such work.

The selection course for undercover agents lasts for several months.

Recruits must be able to cope with large amounts of stress without showing any outward sign of pressure and have the ability to develop multiple personalities or "legends".

Dame Stella Rimington, a former director general of MI5, is the only senior member of the organisation to have a book published but she did not delve into the operational activities of the organisation. A book by Richard Tomlinson, a former MI6 agent, was published in 2001 which revealed the inner workings of the Secret Intelligence Service. David Shayler, a former MI5 agent was prosecuted under the Official Secrets Act after passing a secret document to a newspaper in 1997.

A senior Whitehall source said last night: "There is a legal process taking place. It would be wrong to comment further."