GLATTBRUGG, Switzerland, Nov. 1 (UPI) -- Former world No. 1 women's tennis player Martina Hingis admitted she is under investigation after testing positive for cocaine use at this year's Wimbledon.
The BBC reported Thursday the admission came during a news conference during which Hingis announced her retirement from competitive tennis for the second time.
The 27-year-old, Czech-born resident of Switzerland retired in 2002 and returned four years later.
An angry Hingis denied using cocaine.
"I am frustrated and angry," she said. "I believe that I am absolutely, 100 percent innocent (and) considering this situation, my age and the problems I have been having with my hip, I have decided to no longer play tennis on the tour."
The five-time Grand Slam champion was plagued by hip problems in 2007. The injury forced her to end the season Oct. 11 after one title, the 43rd of her career. She is ranked No. 19 in the world.
Larry Scott, the women's professional tour chief executive officier, issues a statement saying: "The Sony Ericsson WTA Tour has not received any official information regarding the positive doping test result referred to by Martina Hingis in her press conference today, and as a result we are not in a position to comment on the matter. In her most recent comeback, she proved again that she can perform at the very highest levels of the game."