The Guardian reports that Mulcaire lost an appeal against an order to disclose who told him to hack the phones of supermodel Elle MacPherson, deputy leader of the Liberal Democrats Simon Hughes, celebrity publicist Max Clifford, football agent Sky Andrew, legal adviser to the Professional Footballers Association Jo Armstrong, and former head of the PFA Gordon Taylor.
The order is the result of legal action by actor and comedian Steve Coogan, who said in a statement: "Whilst I am pleased with this latest development I remain frustrated by Mr Mulcaire's refusal to answer questions about who authorised him to unlawfully access my voicemail messages and will continue to press for these answers."
Mulcaire is set to name the names by the end of next week.
Meanwhile, a British police detective was arrested Thursday on suspicion of having leaked details to the press about the police investigation into the News Of The World. The Guardian reports that he was not charged, but was suspended by Scotland Yard.
Scotland Yard's Deputy Assistant Commissioner Sue Akers called the arrest "hugely disappointing."
"I made it very clear when I took on this investigation the need for operational and information security. It is hugely disappointing that this may not have been adhered to," she said.
Another former NOTW, reportedly Dan Evans, was arrested and released on bail on Friday in connection with the wide-ranging phone hacking scandal.