Tennis authorities have rejected claims they deliberately suppressed evidence of widespread match-fixing at the top level of the sport.
An investigation carried out by the BBC and Buzzfeed alleges that over the last decade a core group of 16 players have repeatedly been brought to the attention of the sport's governing bodies over suspicions they have fixed matches.
The report claims all of the 16 players have ranked in the world's top 50 and more than half of them were playing in the Australian Open first round, which started on Monday.
The BBC said the group also included "winners of Grand Slam titles".
It is alleged that in 2007 tennis authorities were presented with an examination of 26,000 matches, three of them at Wimbledon, which contained enough evidence to root out offenders - but no action was taken.
In a press conference summoned at Melbourne Park on Monday morning, ATP president Chris Kermode refuted the claims.
"The Tennis Integrity Unit and the tennis authorities absolutely reject any suggestion that evidence of match fixing has been suppressed for any reason or isn't being thoroughly investigated," Kermode said.
"And while the BBC and BuzzFeed reports mainly refer to events from about 10 years ago, we will investigate any new information, and we always do.
"In its investigations, the Tennis Integrity Unit has to find evidence as opposed to information, suspicion, or hearsay."
Kermode continued: "Let me just say that all of us here in tennis are absolutely committed to stamp out any form of corrupt conduct in our sport. There is a zero tolerance policy on this."
It is alleged that one top-50 player competing in the first round of the Australian Open is suspected of repeatedly fixing his first set.
The Tennis Integrity Unit was set up in 2008 to tackle corruption within the game. The organisation's director Nigel Willerton refused to confirm whether players competing at the Australian Open are currently under investigation.
Willerton said: "It would be inappropriate for me to make comment as to whether any players are under investigation at the present time."
The BBC and Buzzfeed say the 2007 referrals were made after an investigation following suspicious betting patterns during the match between Nikolay Davydenko and Martin Vassallo Arguello, of which both men were acquitted.
A confidential report was then handed to tennis authorities in 2008 in which the enquiry team said 28 players should be investigated but the findings were never followed up, it is alleged.
Kermode said: "We have heard this quite a bit, that there are certain allegations and information about various players, and they can be sometimes seen to be a consistent group.
"But it's about obtaining evidence. You can have lots of information, lots of anecdotal reports, but it's about getting evidence that we can use.
"So anything that is reported to the Tennis Integrity Unit is acted upon and is investigated, and that's, again, a very important message to get across.
"This doesn't just sort of filter out somewhere. It is acted upon."
Willerton added: "That is correct. I will confirm that very strongly. Everything that comes into the unit is actioned, it's assessed.
"But as I say, corruption is very difficult to detect and to obtain the evidence to prosecute these people who unfortunately go down that path."