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A ban on terrorists being released early from jail was announced tonight after Times Online revealed that a convicted terrorist was freed 17 days early under plans to ease overcrowding.

Jack Straw, Justice Secretary, was forced to alter Government policy after today’s revelation that Yassin Nassari was freed from a maximum security prison just seven months after a three-and-a-half-year sentence was handed down.

The controversial early release scheme, known as end of custody licence (ECL), was introduced last year to create more space in the UK’s overcrowded prisons. The Government insisted that only “non-violent” offenders would be freed early, but Nassari was convicted of trying to smuggle missile blueprints into the country.

The Ministry of Justice announced this evening that a second man convicted of terrorism offences had also been released early under the scheme.

Mr Straw tightened the guidelines to stop any further terrorists being freed around five hours after a Times Online story detailed Nassari's release.

“In the light of this case I have taken action to tackle this issue - no more prisoners convicted under terrorism legislation will be released through the ECL scheme,” Mr Straw said.

News of Nassari’s release plunges the Government’s terrorism policy into chaos just days before a crucial Commons vote on plans to increase the maximum period police can question terror suspects to 42 days.

The Liberal Democrats accused Mr Straw of “shutting the stable door after the horse has bolted” and David Davis, Shadow Home Secretary, said: “Jack Straw must now say when he knew about this, and why he has only just acted.

“Was Nassari released with or without his knowledge? If it was without, who on earth is running his department?

“The Government’s perverse approach to security defies common sense. On the one hand, they are trying to pass a new law extending the period for holding innocent people - convicted of nothing - when we already have the longest period of pre-charge detention in the free world.

“On the other hand, they are releasing a terrorist we have managed to bring to justice, a dangerous man convicted in our courts for researching how to deploy military weapons in this country.”

Nassari, 28, from Ealing, west London, was released from the maximum security Wakefield prison on February 11. He had been found guilty at the Old Bailey of possessing documents likely to be useful to a terrorist.

His computer hard drive was found to contain documents about martyrdom and weapons training, as well as instructions on how to construct the Qassam artillery rocket, the type of home-made steel rocket used by Palestinian militants to attack Israel from the Gaza Strip.

Police also found several graphic videos of terrorist attacks and beheadings at Nassari’s home.

He was acquitted of the more serious offence of possessing articles for terrorist purposes.

His three-and-a-half-year sentence had already been cut by 413 days due to the period he spent on remand prior to his conviction.

The second unnamed man was freed from Glen Parva jail in Leicestershire on January 7. It is understood that he had been serving six months for possessing a document or information useful to terrorists.

A Ministry of Justice spokeswoman said that no further crimes were known to have been committed by the two men since they were freed.

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