Jack Straw, the justice secretary, banned the early release of convicted terrorists last night after it emerged that two prisoners had been let out early as part of the government's efforts to ease overcrowding in jails.
Yassin Nassari, who was arrested at Luton airport with a blueprint for a rocket in his luggage, had served just over seven months of a three-and-a-half year sentence when he was released in February from a maximum security prison in Wakefield, 17 days before his official release date. Abdul Muneem Patel, who was 17 when he was arrested in August 2006 after an explosives manual was found at his home in east London, was released in January, three months into a six-month sentence at a young offenders' institution in Leicester.
Hours after the news broke, Straw announced a change to the rules regarding the end of custody licence (ECL) release programme, banning convicted terrorist from the scheme. "In the light of these cases the justice secretary has decided to change the criteria for the ECL scheme so that any prisoner convicted under terrorism legislation would not be eligible," said a spokesman for the Ministry of Justice.
Until Straw's intervention the emergency measures brought in last year allowed any "non-dangerous" inmates to be freed up to 18 days early. The ministry said Nassari's release was justified because he had not been convicted of an offence involving "serious violence". But opposition politicians said it was remarkable either man had been eligible for early release.
David Davis, the shadow home secretary, called the decision "perverse".
"On the one hand [the government] 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," he said.
"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."
He called on Straw to say when he knew the prisoners had been let out.
"Was Nassari released with or without his knowledge? If it was without, who on earth is running his department?" Straw's intervention came days before a Commons vote on government plans to increase the maximum period for which police can question terror suspects to 42 days.
Liberal Democrat justice spokesman Chris Huhne said there was a "huge discrepancy" between the government's rhetoric on terrorism and its actions.
"Next week ministers will bring before parliament unnecessary and draconian legislation on pre-charge detention in a desperate attempt to look tough on terrorism," he said. "People convicted of terrorist offences can be back in society having served less than half their sentence because of our desperately overstretched prison system."
Nassari was found guilty at the Old Bailey of possessing documents likely to be useful to a terrorist. His computer contained documents about weapons training, as well as instructions on how to construct the Qassam rocket - a missile used by Hamas. He denied knowledge of the material, saying he had lent his computer to another man. Nassari was acquitted of the more serious offence of possessing articles for terrorist purposes. His Dutch wife, Bouchra El Hor, 24, was cleared of failing to disclose information about terrorism.
The couple and their five-month-old baby were stopped at the airport in May 2006 on their way home from trips to Syria and the Netherlands.
At the time of his conviction the Metropolitan police deputy assistant commissioner, Peter Clarke, said Nassari held the "ideology, ability and determination to find and download material which would have been useful to terrorists".
Clarke, now retired, said Nassari's intentions on arrival in Britain were unclear.
"However, it is possible that his research could have ended up in the hands of individuals or groups willing to put it into practice," he added.