PARIS (AP) — French anti-doping officials are worried about the increased use of cocaine by athletes to enhance their performance.

Damien Ressiot, who is in charge of controls at French anti-doping agency AFLD, said Tuesday that taking the banned stimulant for doping purposes now seems to be a "fairly common practice."

Cocaine is among a class of stimulants whose use is banned only in competition.

Speaking at a news conference at AFLD headquarters, scientific adviser Xavier Bigard insisted it would be "extremely dangerous to minimize its use as a purely recreational drug."

Ressiot added that several cases involving cocaine use which are currently under the scrutiny of the AFLD will help the agency determine the type of networks used by cheaters.

Earlier this year, former Wallabies back James O'Connor was fined for cocaine use by the Paris prosecutor's office and suspended by his club Toulon. The 26-year-old O'Connor and former All Blacks lock Ali Williams spent more than 24 hours in custody after they were arrested outside a nightclub for buying cocaine.

After the incident, Toulon president Mourad Boudjellal said he had the feeling cocaine had become a popular drug in his sport.

Bigard said cocaine use is particularly present in sports where power and strength are required to excel.

"The president of the French Rugby League federation also said cocaine was a problem in elite sport," Ressiot said.

There have been several cases involving cocaine in the world of sports recently. Last November, Finnish soccer player Roman Eremenko was banned for two years after a positive test for the stimulant. The Court of Arbitration for Sport also gave Algeria forward Youcef Belaili a two-year ban on appeal for cocaine, and rugby league player Ben Barba was released by the Cronulla Sharks in Australia after testing positive for the drug.

Former boxing world champion Tyson Fury also admitted taking cocaine after he had his license suspended over drug use and medical issues.

Presenting the agency's activity report for 2016, AFLD president Bruno Genevois said endurance sports traditionally hit by doping, a group that includes cycling and track, have made big progress in the fight against doping.

"When you compare the number of doping cases with the number of the sports practitioners, the World Anti-Doping Agency's statistics show that body building and weightlifting are" the sports the most exposed to doping, Genevois said.

Ressiot added that the agency was also making a priority of testing athletes competing in combat sports like mixed martial arts.

"Although they remain banned in France, mixed martial arts are very popular among youngsters," Ressiot said. "And the substances involved are heavy, anabolic steroids."

Ressiot and Genevois also rued a lack of cooperation from the International Tennis Federation that again prevented the AFLD from being involved in the testing process at the French Open this year.

"We have real issues with the ITF, a federation which has the deepest contempt for national anti-doping agencies," Ressiot said.