In the report the Independent Police Complaints Commission (IPCC) said:
"There is no doubt, from our investigation and the evidence gathered by Operation Baronet, that Surrey Police knew in 2002 of the allegation that Milly Dowler’s phone had been hacked by the News of the World (NOTW).
"It is apparent from the evidence that there was knowledge of this at all levels within the investigation team.
"There is equally no doubt that Surrey Police did nothing to investigate it; nobody was arrested or charged in relation to the alleged interception of those messages either in 2002 or subsequently, until the Operation Weeting arrests in 2011."
More top news
A driver who left two sisters paralysed after his 4x4 smashed into their family car during a road rage chase, has been jailed.
Chinese laundry detergent ad has been called out as 'the most racist advert ever' on social media after the video was picked up online.
Vote Leave launch £50m competition you can win if you successfully predict every single match in the European Championships.