Black-cab rapist John Worboys could be freed within weeks after the Government opted not to challenge his release.

Justice Secretary David Gauke said it would not be appropriate to seek a judicial review of the case after taking "considered and expert" legal advice.

An outcry erupted earlier this month after the Parole Board directed the release of Worboys, 60, after a decade behind bars.

He was jailed indefinitely in 2009, with a minimum term of eight years, for drugging and sexually assaulting women passengers.

Worboys was convicted of 19 offences against 12 victims but has been linked to more than 100 complaints in total.

Last weekend it emerged Mr Gauke had commissioned advice on the possibility of taking the highly unusual step of seeking a judicial review.

The Ministry of Justice had said he would only proceed "if there is a reasonable prospect of success".

Speaking in the House of Commons, Mr Gauke said: "I know that the victims of these crimes have suffered significant emotional trauma.

"The prospect of the release of this man is deeply concerning to them, to many members of this House and to the wider public.

"I believe that I owe it to those victims and to the public to consider all the options open to me as Lord Chancellor and Secretary of State for Justice.

"I therefore took the step of seeking legal advice from specialist leading counsel to establish whether there were grounds to challenge this decision in the courts and therefore to ask the court to stop the release of Worboys before the decision was reconsidered."

But, he added: "Having taken considered and expert legal advice I have decided it would not be appropriate for me as Secretary of State to proceed with such a case. Honourable members will appreciate that I cannot go further and expose detail of the legal advice I have been given."

Shadow justice minister Imran Hussain said: "Many will be disappointed by today's news. It is understood that legal advice can't be shared and the minister does not want to prejudice other cases being brought.

"But today's news makes the need for changes in the Parole Board even more pressing."

Mr Hussain told MPs: "We welcome the widening of the review announced today, and especially a mechanism to allow Parole Board decisions to be reconsidered while retaining its independence."

In reply, Mr Gauke said he "shares the instincts" of Mr Hussain over the need for greater transparency in decisions.

Bob Neill, Conservative chairman of the Justice Committee, said: "A political and policy decision that could be made as soon as possible is to change the Parole Board rules to permit the Parole Board to give reasons for its decisions."

Mr Neill said such a move is likely to have cross-party support and the Parole Board's backing.

Mr Gauke continued: "I have taken a close personal interest in this case since assuming office as Secretary of State for Justice. I believe it is important that all the victims have clarity as soon as possible which is why I am before the House today.

"I can reassure the House and the public that Worboys will not be released until his licence conditions have been finalised."

Richard Scorer, a specialist abuse lawyer at Slater and Gordon which previously represented 11 of Worboys' victims in a civil case, said:

"Although our clients are disappointed that the government has chosen not to participate in a judicial review of this decision, the victim judicial review is going forward and we urge everyone to support it and support the crowdfunding efforts.

"It is crucial that the decision to release this manipulative, calculating and dangerous man can be considered by the courts as soon as possible.

"It is also imperative that the failure to prosecute more cases against Worboys is re-examined."