Scotland Yard detectives tell high court hearing that number of victims may be bigger than previously thought

Scotland Yard's renewed investigation into phone hacking at the News of the World has identified that the number of victims is in excess of 91 people – far higher than previously estimated by detectives, the high court heard today.

The publisher of the newspaper has also offered Sienna Miller £100,000 in compensation and offered to pay the actor her costs – an offer she has neither accepted nor rejected.

Detectives are trawling through 9,200 pages of material seized from a private investigator used by Rupert Murdoch's tabloid to hack into voicemails, a case management hearing to decide how best to handle the flood of lawsuits against the paper heard.

At the hearing in the high court, Jason Beer QC, representing the Metropolitan police, gave an idea of the scale of the scandal. Beer said that the number of potential victims is "substantially" higher than 91 people.

The figure of 91 is significant. Previously police had said they had recorded a total of 91 pin numbers – necessary to access a mobile phone's voicemail – in the possession of Glenn Mulcaire, the private investigator employed by the News of the World.

The police counsel told the hearing: "It is wrong to say that 91 is the answer, that that is the maximum [number of victims], it may be on a bigger scale."

The court hearing also heard of the offer to Miller, which was designed to reflect the number of times her phone had been targeted. Her case is one of the most advanced of the phone-hacking lawsuits, and arguably the highest profile because of her celebrity.

Mulcaire was convicted of intercepting voicemail messages in January 2007, along with the News of the World journalist Clive Goodman. During the course of the original investigation, police seized paperwork and records from Mulcaire, who was employed by the tabloid.

Subsequently, John Yates, the Met's acting deputy assistant commissioner, who handled a previous phone-hacking investigation, said that the police had only identified 10 to 12 victims. That figure is far lower than the level identified by the fresh investigation team, which is under the leadership of deputy assistant commissioner Sue Akers.

Yates said earlier this month that he had quoted the figure on at least four occasions because prosecutors had told police they needed to prove not only that voicemail had been intercepted but also that this had been done before the messages had been heard by the intended recipient.

So far, 24 public figures who believe their voicemail messages were intercepted by journalists at the tabloid are suing News International, the UK newspaper arm of News Corp.

Many more are expected to come forward after News International apologised to eight victims last week and said it would set up a compensation scheme.

Law firm Mishcon de Reya, which is acting for several of the claimants, says it has received an unprecedented number of inquiries since News International published its statement, and estimates there could be more than 6,000 potential claimants.

Judge Justice Vos said that four test cases – those of Sky Andrew, Kelly Hoppen, Sienna Miller and Andy Gray – could be heard as early as December, but no later than February 2012.

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