John Worboys is to remain in prison for at least another 2 years.
The former Bournemouth and London cabbie may also face new sexual assault charges.
61 year old Worboys, was convicted in 2008 of committing 19 offences, including rape, sexual assault and drugging against 12 victims, although it is believed that the true figure may be significantly higher.
The parole board had originally agreed to free Worboys in January 2018, but that decision was over-turned in March 2018.
According to reports in The Daily Mail evidence has been passed to the Crown Prosecution Service, which may see Worboys charged with more offences committed between 1997 and 2007.
The latest string of charges facing Worboys include an alleged sexual assault and administering a substance with intent to commit a sexual offence.