Justice Secretary David Gauke is considering launching a judicial review in a bid to stop the release of black cab rapist John Worboys.
The government said Mr Gauke had sought legal advice on an attempt to reverse a Parole Board decision to free the serial sex attacker.
A Ministry of Justice spokeswoman said: “The Secretary of State commissioned mid-last week advice on the plausibility and the prospect of success in a judicial review.
“He would only be minded to move forward on a Judicial Review if there was a reasonable prospect of success.”
London cab driver Worboys was jailed indefinitely in 2009, with a minimum term of eight years, for drugging and sexually assaulting female passengers.
He was convicted of 19 offences relating to 12 victims but is suspected of being one of the country’s most prolific sex offenders. Police believe he could have attacked more than 100 victims in total.
The Parole Board’s decision to release him after nine years sparked