Timeline: Shayler spy row

David Shayler: Left MI5 in 1997

As former MI5 officer David Shayler is released from prison early after breaching the Official Secrets Act, BBC News Online charts the progress of the UK's biggest spy row since the 1980s.

1997
MI5 officer David Shayler leaves the Intelligence Service after six years.

August: Shayler supplies damning details of MI5 operations to the Mail on Sunday newspaper. They include the accusation that the government kept secret files on politicians who are now cabinet ministers. Mr Shayler leaves the UK after the allegations are published.

September: Annie Machon, Shayler's partner, is arrested on arrival at Gatwick airport. She is released after six hours of questioning by Special Branch.

1998
July: Shayler accuses MI5 of failing to react to an impending terrorist attack on the Israeli Embassy in 1994. He also says MI6 officers plotted an assassination attempt against Libyan leader Colonel Gaddafi in 1996.

August: Shayler is arrested in France and held without charge for nearly four months in a Paris jail.

November: The UK Government's attempts to extradite Shayler are rejected by a French court. Shayler says he will not make fresh revelations about the UK's secret services and attempts to get charges against him dropped.

1999
August: Shayler threatens to reveal more MI5 secrets - this time via the internet. He claims that the intelligence information is already stored on his computer and could be released at the push of a button.

September: Shayler compares his treatment with that of Melita Norwood - the elderly spy whose activities had been known about by MI5 since 1992. He claims MI5 is vindictive against him because he has embarrassed it with his revelations.

December: Shayler launches a campaign to return to the UK.

2000
February: The government issues a writ against Shayler for breaches of confidence, contract and copyright laws on files held by MI5 and the British overseas secret service, MI6.

March: Shayler's partner, Annie Machon, hands a dossier of documents he has prepared about the alleged Gaddafi assassination plot to the headquarters of Special Branch.

May: To mark his 1,000th day in what he calls "political exile", Shayler plans to mount a crucifix outside the British Embassy in Paris in protest of his treatment by the British Government. He is not allowed to go through with his plans.

July: Shayler's novel, The Organisation, is passed by the government censors. Described as "a gritty thriller about spies, sex and football", he wrote it while living in France.

A High Court judge quashes an order made in March which required the editors of The Guardian and Observer to hand over documents and e-mails sent to them By David Shayler.

The court warned against the making of court disclosure orders against newspapers which might "stifle" investigative journalism unless there was "compelling evidence" the orders were in the public interest.

August: Shayler is charged under the Official Secrets Act within hours of arriving back in Britain at the end of three years of self-imposed exile.

2001

May: The High Court refuses Shayler permission to defend the accusations that he revealed state secrets on public interest grounds.

November: Shayler is told he can appeal to the House of Lords in his attempt to plead public interest at his forthcoming trial.

2002

March: The House of Lords rejects any use of a public interest defence in Shayler's trial.

Law lords unanimously decide there is no incompatibility between the 1989 Official Secrets Act, under which Shayler faces prosecution, and Article 10 of the European Convention on Human Rights guaranteeing "freedom of expression".

October: Trial on three counts of exposing official secrets begins at the Old Bailey in London.

November: Shayler is found guilty on all three counts and jailed for six months.

December Shayler leaves prison after serving less than seven weeks for breaching the Official Secrets Act.

He is expected to spend another seven weeks electronically tagged under the Home Office's home detention curfew scheme.