One of Australia's most respected tennis players says he suspects there are players using performance-enhancing drugs.

Mark Woodforde, a winner of 11 grand slam doubles titles including six Wimbledons, said it would be naive to think that tennis is drug free.

The now-retired Woodforde stopped short of identifying any players he suspected of cheating but told Australian radio he is not alone in his suspicions.

"I would love to think that our sport is totally clean, but I think, I, amongst numerous other players, you have to wonder occasionally," he said.

While some of the top players are divided over the introduction of blood tests at this year's Australian Open, Woodforde said the more stringent tests are necessary if the sport wants a clean image.

"I think it just puts us on a level pegging, so to speak, with other sports that have stringent testing," he said.

"If there's one question in anybody's mind how clean our sport is, that's one question too many.

"So I would have no problem personally going the extra mile for the sake of removing any question that may exist."

Woodforde's comments followed days after the ATP announced it planned to double the number of out-of-competition tests this year.

Male players were told at a meeting in Melbourne on Saturday night that testing teams would be given greater resources to demand to test players at their homes and training bases in 2003.

The Australian Open, which started on Monday, is the first tournament at which blood tests are taken to test for the banned endurance booster erythropoietin (EPO).

The ATP, Women's Tennis Association and International Tennis Federation adopted International Olympic Committee standards from January 1, and a Swedish drug agency will take the blood tests.

Random out-of-competition tests are commonplace in other sports and while most tennis players, including former world number one Andre Agassi, say they are in favour of EPO testing, not everyone is happy.

Russian Marat Safin, seeded third at the Open, is stridently opposed to the idea, arguing that doping is not a major problem in tennis.

Safin said some players feel faint at the sight of a needle and that the new policy would cause problems. But players who decline a blood test would be banned for two years, the same period of suspension as for a positive test for EPO.

Former Australian Open champion Petr Korda was banned for a year after testing positive for steroids at Wimbledon in 1998 and in the past two years, Argentine players Juan Ignacio Chela and Guillermo Coria, were also handed stiff penalties following positive dope tests.