Black-taxi rapist John Worboys has been moved to a London jail ahead of his release.
The notorious sex offender was transferred from HMP Wakefield in West Yorkshire to HMP Belmarsh, south-east London, at the weekend, it is understood.
Both Wakefield and Belmarsh are high-security prisons.
News of the move, first reported by The Sun, follows a furore over the Parole Board's decision to direct Worboys's release after a decade behind bars.
The 60-year-old 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.
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.
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.
When he is released, 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.