A Tennis Integrity Unit investigation also revealed that the only confirmed criminal case of tennis match fixing in Australia was significantly wider than was first thought, raising further questions about the conduct of the nation's young players.

The TIU confirmed in a statement that Nick Lindahl, Brandon Walkin and Isaac Frost were all found to have committed corruption offences in relation to a match at a tournament in Toowoomba in 2013.

Lindahl, 28, was banned for seven years and fined $US35,000 ($48,000) for his role in the fix, which occurred at a Futures tournament in Toowoomba in September, 2013.

Walkin, 22, was hit with a six-month suspension, suspended for six months, and Frost, 28, with a year suspension, which he has already served.

Lindahl and another former player, Matthew Fox, are the only people to have faced criminal charges in connection with the fixed match.

Both were convicted.

A coach and another player, Adam Feeney, were also linked to the case, but were never charged.

The involvement of Walkin and Frost, neither of whom had been highly-ranked but who regularly played in tournaments in Australia and internationally, indicates that at least five players were aware of Lindahl's match fixing.

Fairfax Media revealed last week that Oliver Anderson, the reigning Australian Open boys champion, had been charged by Victoria Police with match fixing offences in relation to a tournament in Traralgon last October.

It is understood Mr Anderson was approached to drop the opening set of his first-round match at the tournament.

Investigations are continuing into the syndicate that approached Anderson, but it can be revealed that Walkin and Dayne Kelly, who had been coached by his close friend Lindahl, both played at the tournament.

There is nothing to suggest they are linked to Anderson's case, and it is unclear whether Lindahl had attended the tournament.

Tennis figures expressed serious concerns for more than two years about a core group of players and coaches linked to Lindahl who they suspected were involved in corruption.

Those fears have been laid bare by the TIU investigation, which waited until the criminal case against Lindahl finished last April before completing its disciplinary action.

Independent anti-corruption hearing officer Richard McLaren found Lindahl proposed to lose a match for money at the Australian F6 Tournament on September 11, 2013.

The former world 187 was found guilty of charges of contriving or attempting to contrive the outcome of an event, and failing to co-operate with a TIU investigation.

He then failed to hand his phone to integrity officials for a forensic analysis, the investigation found. Lindahl has been provisionally suspended since October, 2013.

Walkin, who has a career-high ranking of 1062, was found to have passed a "corrupt proposal" to another person on behalf of Lindahl.

It is understood the charge relates to Walkin approaching wildcard player Andrew Corbitt, Lindahl's opponent in the Toowoomba match, and telling him that Lindahl would "tank" the match so that Corbitt could gain his first ATP ranking point.

Walkin was found guilty of contriving or attempting to contrive the outcome of an event, but, because his penalty was suspended for six months, is free to compete in professional tennis matches.

Frost, who reached his highest ranking of 458 five years ago, also failed to surrender his phone to TIU officials, and was provisionally suspended from October 3, 2013 and September 4, 2014, for failing to co-operate.

Mr McLaren concluded that no additional suspension or any fine should be imposed.

It remains unclear why a provisional suspension was not issued against Walkin. The TIU has been contacted for comment.

On July 18, 2014, Victoria Police moved on the only confirmed criminal case of tennis match fixing in Australian history.

Six men were arrested on suspicion of betting on fixed tennis matches

Only one of the men, Fox, was charged.

Phone records showed that on September 11, 2013 - the day of the Toowoomba match between Lindahl and Corbitt - Lindahl called Fox four times.

Fox placed a number of bets on the match, using accounts in his name and others, police found.

Sportingbet suspended betting because of a plunge on the relatively minor match.

Fox was found to have made a profit of $1416 through Sportsbet, but was suspected of further winnings with other bookmakers.

Police established that associates of Fox and Lindahl also betted on Corbitt to win the match, which he did 6-2, 6-3.

On October 29, 2013, Adam Feeney played Japanese qualifier Bumpei Sato at the Traralgon Challenger tournament - the same tournament where Anderson would allegedly fix a match three years later.

Australian betting agencies reported suspicious betting patterns on the match, and identified that a number of people who bet on the Lindahl-Corbitt clash had also bet on Sato to beat Feeney.

Feeney was found to have fixed the match and lost 4-6, 4-6.

Fox was believed to have made at least $2718 from this match, but, as police said during his court case the following year, the number of betting accounts he used could not be confirmed, so his total profits could not be determined.

Phone records showed him contacting Feeney days after the match.

Lindahl was charged by NSW police in February 2015, after Victoria Police were unable to prosecute him because of a hole in the state's match fixing laws.

A Tennis Australia spokeswoman said that under the Tennis Anti-Corruption Program, Tennis Australia could not issue sanctions for corruption related offences.

All sanctions were issued by an anti-corruption hearing officer - such as Mr McLaren - appointed by the TIU. The TIU only comment publicly on an investigation once a hearing has taken place and a finding has been made.

"Tennis Australia has, and will continue to, support the efforts of the authorities to help remove corruption from tennis," the spokeswoman said.