The former MI5 agent David Shayler has lost the first stage in his High Court battle over charges that he breached the Official Secrets Act.

Shayler had sought to argue in court that his revelations about the work of MI5 to the Mail on Sunday, which led to three charges being brought against him, had a public interest defence.

Shayler has already announced he will appeal against the ruling, which related to whether, or to what extent, the OSA was subject to the free speech guarantees set out in the Human Rights Act.

The Crown has argued that the OSA created "absolute offences" which rendered free speech issues inapplicable.

Speaking after his defeat, Shayler said: "If the Human Rights Act has no bearing here, then we can only conclude that it is simply more bureaucratic window dressing to hide the fact that Britons have fewer rights over the government than citizens elsewhere in the West."