“Black cab rapist” John Worboys has admitted drugging four more women.
The 62-year-old, who was jailed in 2009 for a string of sex attacks, entered his plea at the Old Bailey.
He pleaded guilty to two counts of administering a drug with intent to commit rape or indecent assault. He will be sentenced on 2 September.
Worboys, who now goes by the name John Derek Radford, targeted 12 women who hailed his cab and drugged them in order to sexually assault them.
The taxi driver, originally from Enfield, was jailed in 2009 for at least eight years for the attacks, which were carried out in London between 2000 and 2008.
At a hearing at the Old Bailey earlier, he pleaded guilty to further offences relating to four more women.
They included two counts of administering a stupefying or overpowering drug with intent to commit rape or indecent assault and two of administering a substance with intent to commit a sexual offence.
Worboys was told after his first trial he would be held in custody as long as he was deemed a danger to the public.
Last year, the Parole Board ruled he should remain in prison citing his “sense of sexual entitlement” and a need to control women.