The parents of murdered schoolgirl Milly Dowler were dealt a further blow when the Leveson Inquiry heard it would never be known if her voicemails were deleted.

Sitting on May 9, the inquiry heard at least two messages were missing.

But Metropolitan Police lawyer Neil Garnham QC said there was no evidence they had been erased by journalists from the News of the World.

Although there was evidence they had been listened to, he said automatic deletion of the messages could not be ruled out.

He told the inquiry: “In summary, we cannot conclusively say whether any voice mails were or were not manually deleted.

“However there appear to have been two messages missing that should have been present when Surrey Police carried out their second recorded download on April.

“It’s not known why that happened and it will not now be possible to provide an explanation.”

David Sherborne, counsel for the Dowlers and other phone hacking victims, said a cocktail of ingredients was responsible for confusion over how the voicemails were deleted.

He cited these as the failure of Surrey Police, the decision of the Met to close the 2006 hacking investigation and concealment by News of the World senior staff.

He said: “While some questions stay, and may always remain, unanswered there are some to which we do know the answer.

“The News of the World did hack into Milly Dowler’s phone searching for a scoop at a time when she had already been murdered. That fact alone is horrifying enough.

“We also know that the newspaper interfered seriously with the police investigation trying to use the information they had illegally obtained to get an exclusive on Milly’s movements.

“Thirdly this inquiry investigating as it has done the practices, culture and ethics of the press would have happened regardless of the question which arose at the start of the evidence that Sally Dowler’s false hope moment may have been the result of activity of someone at or working for the newspaper.”