Melbourne: Match-fixing is commonplace in tennis' lower levels and efforts to fight it are inadequate, a senior anti-corruption official told AFP after cheating claims rocked the sport during the Australian Open.

After an explosive report claimed match-fixing was repeatedly going unpunished, Chris Eaton of the International Centre for Sport Security (ICSS) criticised tennis' "opaque and secretive" anti-corruption body.

The controversy is the latest to hit the tainted sports world after claims of a doping cover-up hit athletics and multiple scandals engulfed football's governing body, FIFA.

Eaton, director of integrity at the ICSS, said professional betting analysis showed 'nil manipulation' of matches at the top levels of tennis, where players are highly paid and less susceptible to bribery.

"However, in the second and lower levels, manipulation indicators are heavy and regularly occurring. "We are not the only sport integrity organisation to observe this," the former FIFA security chief said via email.

Eaton's comments follow the BBC and BuzzFeed report that said 16 players, who had reached the top 50 over the past decade had repeatedly been suspected of fixing matches, but never punished.

Three matches at Wimbledon had fallen under suspicion and at least eight of the "core group" of players on the fixing radar were at the Australian Open, which began on Monday, it said.

Tennis authorities rejected any suggestion that evidence was suppressed and defended the working of the Tennis Integrity Unit, which was set up in 2008 and has landed 18 convictions, with six life bans.

The BBC and BuzzFeed report's claims are backed by anecdotal evidence given by World No 1 Novak Djokovic, who said he was once offered $200,000 to fix a match in Russia. Former US ace Andy Roddick said a fellow former professional had told him he could probably name "at least 8-9" of the 16 suspected of repeatedly fixing matches.