A FORMER MI6 officer was last night facing the prospect of up to two years in jail after pleading guilty to unlawfully disclosing information under the Official Secrets Act.

Richard Tomlinson, 34, was remanded in custody for sentencing at the Old Bailey after he admitted attempting to publish a book in Australia about his experiences in the Secret Intelligence Service.

He is the first MI6 agent to be convicted under official secrets legislation since the Soviet spy George Blake 36 years ago.

The prosecution only went ahead after it was authorised by the Attorney-General John Morris.

Colin Gibbs, prosecuting, at Bow Street magistrates' court in London, said New Zealand-born Tomlinson had drawn up a seven page type-written synopsis and preface outlining the first seven chapters of his proposed book for Transworld publishers in Sydney.

He said that analysis by SIS staff showed it contained details of SIS ''training, operations, sources and methods'' and that disclosure would be damaging to national security.

The court heard that the case arose after Tomlinson's employment with SIS was terminated in 1995, four years after he joined. His application to have his claim for unfair dismissal heard by an industrial tribunal was blocked by the then Foreign Secretary Malcolm Rifkind.

He responded by threatening to set up a consultancy on SIS matters and to publish on the Internet a book about his experiences. He was also in contact with the Sunday Times, which published a series of articles about his case without naming him.

Mr Gibbs said Tomlinson complained to SIS about his financial difficulties and his ''disgraceful'' dismissal which had ''eroded his once unshakeable loyalty'' to the service.

Earlier this year, he reached an agreement with SIS to terminate his claim for unfair dismissal and to return information in his possession in exchange for financial support and a promise that he would not be prosecuted for past breaches of the Official Secrets Act.

However, in March he indicated he was not happy with the agreement and shortly afterwards went to Australia, where he had talks in Sydney with a book editor and publisher with Transworld. He also reopened correspondence with SIS seeking permission to publish a book.

After returning to Britain, Tomlinson was arrested on October 31 in Milton Keynes, Buckinghamshire and charged with disclosing ''without lawful authority, information to another which had been in your possession by virtue of being a member of the SIS''.