BERNE, Switzerland The WTA tour said on Thursday it had received no official information about a positive dope test by former world number one Martina Hingis but paid tribute to her achievements as a player.
Hingis told a media conference in Zurich she had tested positive for cocaine during this year's Wimbledon tournament and announced her retirement but insisted she had no knowledge of how the substance had entered her body.
"The WTA Tour has not received any official information... and as a result we are not in a position to comment on the matter," said CEO Larry Scott in a statement released shortly after Hingis's media conference.
Scott said the Tour had a "zero tolerance policy when it comes to doping in sport" before acknowledging Hingis's accomplishments.
"With respect to her retirement announcement, Martina Hingis is a tremendous champion and a fan favourite the world over. In her most recent comeback, she proved again that she can perform at the very highest levels of the game."
"Martina will always be respected for not only having achieved the Sony Ericsson WTA Tour world number one ranking, her five Grand Slam singles titles, nine Grand Slam women's doubles titles and two Sony Ericsson Championships titles, but just as much for her incredible touch, on-court intelligence and off-court professionalism."
Switzerland's national tennis association also praised Hingis's on-court attributes and success.
"Martina Hingis was a great player who was always a role model and a figurehead for Swiss tennis," said association president Rene Stammbach.
"It was Martina who was able to take Swiss tennis to new highs in the Nineties and motivate countless people around the world to play tennis.
"We regret very much that Martina is ending her career faced with these recriminations."