LONDON — A British court ordered a parole board on Wednesday to reconsider its decision to release a notorious sex offender — a former London cabdriver implicated in attacks on more than 100 women — and told the government to lift the shroud of secrecy over parole decisions.

The decision to grant parole to the serial rapist, John Worboys, after a decade in prison prompted outrage when it was made public in January, and two of his victims sought to have the result overturned in court. Victims said they had been assured that Mr. Worboys stood little chance of ever being released, and some said that the authorities had failed to notify them that he was up for parole.

The women said they felt not only betrayed by the decision but also frightened, because Mr. Worboys, who drove them home after drugging and assaulting them, knew where they lived.

On Wednesday, a three-judge panel of the High Court of Justice in London ruled that while it did not have the power to affirm or reverse a parole decision, it was sending the case back to the parole board for rehearing, temporarily blocking the release of Mr. Worboys, 60.