"That said, we have found no evidence of any 'Mafia' involvement in corrupting the integrity of tennis," the review said. "We do not doubt that criminal elements may be involved in seeking to subvert or corrupt some players-officials and that they may even involve organized criminal gangs."

Betting in tennis was put in the spotlight last year after fourth-ranked Nikolay Davydenko withdrew against 87th-ranked Martin Vassallo Arguello in the third set of a match in Poland because of a foot injury.

An online betting site, in an unprecedented move, voided all bets on the match because of suspicious betting patterns.

Since the Davydenko match, others have said they have been approached by outsiders trying to influence a match.

Belgian player Gilles Elseneer said he was offered - and turned down - more than $100,000 to lose a first-round match against Potito Starace of Italy at Wimbledon in 2005.

"There are strong intelligence indications, however, that some players are vulnerable to corrupt approaches and there are people outside tennis who seek to corrupt those within the sport," the review said.

Five Italian players have thus far been found guilty of betting on tennis and have been fined or suspended.

In February, the French Open filed suit in a bid to ban online gambling companies from offering bets on the Grand Slam tournament, but last month a Belgian court ruled in favor for the betting companies.

The French Open starts on Sunday.

Besides noting the 45 matches still to be investigated further, the review panel made 15 recommendations that the four bodies accepted, including agreeing upon a uniform anti-corruption program and an integrity unit.

"The findings of this review clearly demonstrate the need for having an integrity unit," said Jeff Rees, one of leaders on the independent review.

"The aim to rid any uncertainty or implication of corruption in tennis is fundamental to the reputation and future standing of the game and is fully supported by all international tennis bodies."

Another of the recommendations allows only players and essential tournament personnel to have access to the locker rooms at tournaments. The report said many believe that insider knowledge, such as a player's injury or illness that is not widely known, gets passed on to bettors from people inside the locker rooms.