Former British spy David Shayler has threatened to make more embarrassing disclosures about the security services after the government said it was suing him over secret files.

Mr Shayler said he was furious that he was being pursued through the civil courts and added: "If the government want to do battle then I'll have a battle."

Treasury solicitors accuse Mr Shayler of breaches of confidence and contract as well as flouting copyright laws on documentation held by MI5 and MI6, the intelligence services.

The government also wants damages from the Mail on Sunday newspaper which published Mr Shayler's revelations.

But the ex-MI5 worker - exiled in Paris - told BBC News Online that the writ was just the latest move in the government's "personal persecution" of him after efforts to extradite him to Britain failed.

Mr Shayler said he would defend the action on the grounds that the original injunction on his comments about the secret services, was a breach of his human rights.

"When the government first moved, I was arrested and thrown into a French jail, my friends were also arrested on very dubious grounds.

"But the journalists who recorded my remarks were merely asked to help police.

"I am not saying journalists should be arrested for asserting the right to free speech, but it just demonstrates how I am personally persecuted by the government."

Mr Shayler said the government wanted his expenses from the Mail on Sunday and the proceeds from his weekly column in Punch magazine.

"What they are trying to do is cut off my income so I have to return to the UK," he said.

He warned: "It realises I can survive abroad and that I can continue to cause embarrassment."

"I know that MI6 plotted to have Colonel Gaddafi killed but that is a unlawful activity which the government is just not interested in," he added

Freedom law

John Wadham, director of the civil rights group Liberty, said: "What we are seeing is the government taking to the civil courts in their bid to stop David Shayler from acting in the public interest.

"They are using a series of measures to try to make him shut up but we will be fighting this case on the basis that David has the right to freedom of expression and that the public has a right to know about malpractice in MI5."

Mr Wadham said Mr Shayler's defence against the claims would be submitted on Monday.

A trial is unlikely to take place before the end of the year, when the right to freedom of expression becomes enforceable under British law. This is enshrined under the European Charter of Human Rights.

Mr Wadham said the case could become the first test case for the human rights legislation in this country.

Mr Shayler hit the headlines in 1997, when he made a series of claims about the activities of MI5, including revelations that it had kept files on current politicians, including Home Secretary Jack Straw.

He also claims that MI6 was involved in a plot to assassinate the Libyan leader, Colonel Gaddafi.

And he accused ministers of misleading the public over MI5's activities.

Last week, he also claimed to have seen documents showing that former Beatle John Lennon helped fund the IRA.