LONDON — A U.K. Parole Board panel has ordered that a serial rapist believed to have attacked more than 100 women must stay in prison.

The panel ruled Monday that 61-year-old John Worboys, a former London taxi driver who was convicted in 2009 of raping or sexually assaulting 12 women he picked up as passengers, wasn't suitable for release.

The decision overturns an earlier ruling that would have given Worboys parole.

His victims challenged the release, because Worboys was tried on only a handful of cases. They argued the board should have considered that 102 women who made allegations against him.

Worboys has denied committing any offences other than those for which he was convicted.