Surrey Police knew that a News of the World journalist hacked into murdered schoolgirl Milly Dowler's phone in 2002 - but did nothing about it.

A letter from Surrey Police to MPs looking into phone hacking at News International reveals that a reporter openly admitted obtaining Milly's voicemails after getting her mobile number and PIN from school friends at the time of the investigation into her disappearance.

The journalist detailed messages heard on Milly's voicemail inbox, including a tearful message from a relative and someone saying "It's America, take it or leave it".

The heavily redacted letter does not name the journalist or those who left Milly voicemails.

Rather than arrest or investigate the journalist who had obtained the voicemails, senior police officers and communications staff held a meeting with them.

"Surrey Police's ongoing internal investigation is still trying to establish what was discussed at this meeting," said the letter, written by Jerry Kirkby, deputy chief constable at the force.

"It is not known whether information obtained from accessing Milly's voicemail was discussed."

Kirkby insisted that exactly when and how often Milly's voicemails were hacked were matters for the Metropolitan Police's phone hacking investigation, Operation Weeting.

He emphasised that his investigation into Surrey Police's interaction with NotW during the Milly Dowler disappearance was not finished.

NotW closed in July after revelations that its journalists had hacked into Milly's voicemails, as well as families of victims of the London terror attacks in 2005 and a long list of celebrities.

Rupert Murdoch, the media baron who owned NotW, personally apologised to the Dowler family and is believed to have given them a £2m payout.