Secret files showing that international crime syndicates have organized match fixing at the top level of world tennis have come out in the Australian Open.

A joint investigation by the BBC and BuzzFeed News has found that more than 70 players appeared on nine leaked lists of suspected fixers, in which 16 players ranked in the world top 50 including Grand Slam champions and doubles winners at Wimbledon.

According to reports, which was published as the first major of the 2016 Grand Slam—the Australian Open—kicks off Monday; players are being approached in hotels and offered $50,000 (AUD73,100) or more to fix their matches. Gambling syndicates in Russia, Italy and Sicily have made “hundreds of thousands” of British pounds betting on the scores of matches right up to the top level, including Wimbledon and the French Open.

The leaked files came from the 2008 probe, which was triggered by a match in Poland in August 2007 between Russia’s Nikolay Davydenko and Argentine player Martin Vassallo Arguello. The game attracted millions of dollars’ worth of highly suspicious bets from Russian-based accounts. It also showed that Arguello exchanged 82 text messages with the suspected ringleader of an Italian gambling syndicate.