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 a public outcry when it was announced earlier this month.
Previous Justice Secretary David Lidington, who was appointed Cabinet Office Minister in Theresa May’s reshuffle this week, had ordered a review of the board’s transparency amid questions about how the decision was reached.
Sarah Green, from the End Violence Against Women Coalition, said: “The Justice Secretary’s potential attempt to try and stop the release of dangerous serial rapist John Worboys is very welcome.”
Lawyers acting for alleged victims of Worboys have said their clients were “shocked and dismayed” to learn of his imminent release and called for fresh prosecutions.
They said women whose complaints have never been heard in court were told a fresh trial was not necessary because Worboys would “not be coming out for a long time”.
“It is understood that the intention was that ‘the indictment was not overloaded and that the case was as simple as it could be to present to a jury’,” added lawyers Richard Scorer and Harriet Wistrich in a letter to the Crown Prosecution Service (CPS.)
“To the extent that this was the CPS’s expectation at the time, this has clearly not happened and this justification for not bringing further prosecutions has fallen away.”
Mr Scorer said victims were “living in fear” as they await his release and were losing faith in the criminal justice system’s ability to protect them.
A date for Worboys’ release and licensing conditions have not yet been set.
The women whose cases led to prosecutions have been invited to make representations to the Parole Board on the conditions of his release, including contact and exclusion zones.
Some have called for him to be banned from entering London, where the majority of his victims are thought to live.