Secret files exposing evidence of widespread suspected match-fixing at the top level of world tennis, including at Wimbledon, can be revealed by the BBC and BuzzFeed News.
Over the last decade, 16 players who have ranked in the top 50 have been repeatedly flagged to the Tennis Integrity Unit (TIU) over suspicions they have thrown matches.
All of the players, including winners of Grand Slam titles, were allowed to continue competing.
The TIU- which was set up to police the sport - said it had a zero-tolerance approach to betting-related corruption.
Chris Kermode, who heads the Association of Tennis Professionals, rejected claims evidence of match-fixing had "been suppressed for any reason or isn't being thoroughly investigated".
But he added: "While the BBC and BuzzFeed reports mainly refer to events from about 10 years ago, we will investigate any new information."
The cache of documents passed to the BBC and Buzzfeed News include the findings of an investigation set up in 2007 by the Association of Tennis Professionals, the organisation Kermode heads
Hear the whole story on File on 4, Tuesday 20:00 GMT, BBC Radio 4
Its job was to look into suspicious betting activity after a game involving Nikolay Davydenko and Martin Vassallo Arguello.
Both players were cleared of violating any rules, but the investigation developed into a much wider enquiry looking into a web of gamblers linked to top-level players.
The documents we have obtained show the enquiry found betting syndicates in Russia, northern Italy and Sicily making hundreds of thousands of pounds betting on matches investigators thought to be fixed. Three of these matches were at Wimbledon.
In a confidential report for the tennis authorities in 2008, the enquiry team said 28 players involved in these matches should be investigated, but the findings were never followed up.
Tennis introduced a new anti-corruption code in 2009 but after taking legal advice were told previous corruption offences could not be pursued.
"As a result, no new investigations into any of the players who were mentioned in the 2008 report were opened," a TIU spokesman said.
In subsequent years, there were repeated alerts sent to the TIU about a third of these players. None of them was disciplined by the TIU.
A group of whistle blowers inside tennis, who want to remain anonymous, recently passed the documents on to the BBC and Buzzfeed News.
We contacted Mark Phillips, one of the betting investigators in the 2007 enquiry, who told the BBC that they discovered repeated suspicious betting activity about a clear group.
"There was a core of about 10 players who we believed were the most common perpetrators that were at the root of the problem," he said.
He has never spoken publicly about the material he gathered, which he said was as powerful as any he had seen in over 20 years as a betting investigator.
"The evidence was really strong," he added. "There appeared to be a really good chance to nip it in the bud and get a strong deterrent out there to root out the main bad apples." (N24India)