Melita Norwood, 87, promised to fight any court case, but admitted she viewed the prospect with trepidation.

Jack Straw told Parliament the case against former spy was being reviewed following her recent media statements confessing espionage.

The BBC's John Silverman: "A spy trial remains a tantalising possibility"

Shortly afterwards, Mrs Norwood said: "I've brought it all on myself, the whole thing.

"What with Ann Widdecombe having a go and everything I'm not altogether surprised.

"I don't look forward to it, not a bit, but if it comes, I'll just have to lump it. I brought it all on myself."

Jack Straw: Prosecution could still take place

Mr Straw's statement in the House of Commons followed a series of revelations about former spies living freely in the United Kingdom.

Most sensationally, Mrs Norwood was revealed to be the source of secrets passed to the Soviet Union enabling it to build its first nuclear bomb.

A flood of similar stories then emerged as the result of investigations based around information brought to Britain by former KGB chief archivist Vasili Mitrokhin.

Melita Norwood: "I have brought this on myself"

The home secretary told MPs: "The House will be aware that the questions on prosecutions on espionage as for any crime are matter for the law officers, not for the home secretary."

When the attorney general had first learned of Mrs Norwood's espionage, he had believed the last possible date for prosecution would have been in 1992, Mr Straw said.

But her interview given for the BBC's Spying Game series and subsequent statements could have changed the position, he said.

"In the light of Mrs Norwood's recent statements, the papers in this case are currently being studied again by the law authorities."

Mr Straw said four other cases relating to the archives of Mr Mitrokhin were also being considered.

The Crown Prosecution Service will now decide in weeks whether or not to call in the police to investigate the case against Mrs Norwood and the other unnamed former spies.

If the police are asked to investigate, the results of their inquiry would be handed back to the attorney general, Lord Williams of Mostyn, who would make the final decision.

Mr Straw reminded MPs the law stated people were innocent until proven guilty. "We must not slide into trial by denunciation."

David Shayler: "Time-wasting tactic"

Shadow home secretary Ann Widdecombe welcomed the review of the Norwood case.

But she questioned how the government could reconcile its decision not to prosecute so far with its attempts to extradite David Shayler, the former MI5 agent whistleblower.

Speaking from Paris, Mr Shayler told BBC News Online: "This is a time-delaying tactic by the government because if they let her off they'll have to confront my case.

"It's a disgrace - a confession to the press would never stand up in court."

But the journalist who broke the Norwood story for the BBC agreed with the home secretary that the legal position had changed.

"Statements made on videotape could be admissible in court," David Rose told BBC News Online.

Casili Mitrokhin: His records led to the spy revelations

"There is now a potentially realistic prospect of conviction. But then you come to a second issue of whether it is in the public interest to do so.

"My own view is that it would not be. I think it would be somewhat surprising."

If the authorities took a different view, Mr Rose said he would not suddenly be filled with remorse.

"It's not as if we're talking about somebody who inadvertently or occasionally passed on the odd titbit of information," he said. "I stand by the story."

Lib Dem home affairs spokesman Simon Hughes argued it would be wrong to try to bring all former spies to court.