Police are investigating a fresh allegation of historical sexual assault understood to have been made against black cab rapist John Worboys.
The incident was said to have taken place in 1997 and was reported to police this month.
Worboys, who was jailed indefinitely in 2009 - with a minimum term of eight years - for drugging and sexually assaulting women passengers, has not been arrested.
Scotland Yard said in a statement: "The Metropolitan Police Service is investigating an allegation of non-recent sexual assault which was reported to police in January 2018. The incident is reported to have taken place in 1997.
"Enquiries by officers from the Child Abuse and Sexual Offences Command are ongoing."
Meanwhile, news that the notorious sex offender has been moved to a London jail ahead of his release has prompted fresh outrage over the case.
The 60-year-old was transferred from HMP Wakefield in West Yorkshire to HMP Belmarsh, south-east London, at the weekend, it is understood.
Lawyers for victims said the move was "extremely distressing" for them.
News of his transfer, first reported by The Sun, follows a furore over the Parole Board's decision to direct Worboys's release after a decade behind bars.
Worboys was convicted of 19 offences against 12 victims, but has been linked to more than 100 complaints in total.
After the Parole Board's decision was revealed, there were calls for him to be located away from Greater London to reassure terrified victims.
A group of MPs called for an "exclusion zone" to be imposed to ban the former taxi driver from the capital.
Tory MP Zac Goldsmith said the proposed release of Worboys has "absolutely horrified" his victims, who were "appalled" to learn of his move to Belmarsh.
It is understood Worboys's release is not imminent, while his transfer does not mean he will necessarily be freed into the capital.
Last week, Justice Secretary David Gauke stressed that Worboys will not be released until his licence conditions have been finalised, and victims signed up to a contact scheme have had their say on the restrictions.
Upon release, Worboys is expected to spend several months in a probation hostel.
These are staffed 24 hours a day and impose restrictions on residents such as a night-time curfew. There are 101 probation hostels in England and Wales.
A potential legal challenge by the Government over Worboys's release was ruled out by Mr Gauke last week, but lawyers for two victims have said they intend to pursue the case in the courts.
Worboys was convicted of one count of rape, five sexual assaults, one attempted sexual assault, and 12 of administering a substance with intent.
The Ministry of Justice said it does not comment on the location of prisoners.