ATP president Etienne de Villiers told a sports business conference in London today that tennis was being threatened by match fixing and gambling syndicates.

"It's definitely a threat and we take it very, very seriously, and the more you can do to tackle it the better it will be," he said.

The threat of match-fixing in tennis emerged in Poland in August. The online gambling company Betfair voided bets when fourth-ranked Nikolay Davydenko withdrew against 87th-ranked Martin Vassallo Arguello in the third set, citing a foot injury. Unusually large amounts were wagered on the lowly ranked Argentine throughout the match, even after he lost the first set 6-1. The ATP is investigating the match.

Since then, players have said they have been approached about influencing a match. Last month, 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. Arnaud Clement of France said on Monday he turned down money, although he didn't elaborate.

De Villiers said that tennis players who are caught doping should be allowed back after serving their punishment.

"I would draw the distinction with doping," he said. "We have taken the view that also society takes, that you are allowed to make a mistake, you will serve your punishment, but come back into society. The punishment should fit the crime."

There would be no second chances for players who fix matches.

"Where it comes down to match-fixing we are categoric. There is no excuse for that," he said. "You are undermining the integrity of the sport, you are destroying a level playing field. As far as we are concerned in tennis, if they are involved in match fixing they will be thrown out."

The gathering of sports officials and business leaders also heard outgoing World Anti-Doping Agency chief Dick Pound say that some sports were making progress, but others were too slow to keep up with the drug cheats.

"We are dealing with 21st century problems with 19th century organizations," he said. "Out there with many Olympic federations the primary concern of international federation presidents is to be re-elected, not necessarily doing anything. If you want to do something like tackling doping it's a very complicated deal and I find that most of them don't have the stomach for the fight."

Pound said that cycling, and particularly the Tour de France, was paying the price for years of avoiding the problem.