WADA wants funding to keep pace with Rooney-style wage rises

The fight against doping in sport is being severely hampered by a lack of funding, according to the head of the World Anti-Doping Agency (WADA), who complained the body's budget increases have not kept pace with the pay rises of top stars such as Wayne Rooney.

David Howman also claimed that more than 10 percent of elite athletes could be doping, but warned that the number of children using performance-enhancing drugs in order to reach the top was WADA's "biggest concern".

Howman, who will step down as WADA's director general in 2016 after 12 years with the agency, admitted his organisation was suffering from a lack of resources in its attempts to catch drugs cheats.

"When I started at WADA, Wayne Rooney was being paid $4 million (£2.6m) a year by Manchester United," Howman told the BBC. "He's now being paid something like $30m (£19.4).

"We were getting $20m (£12.9) when he first started, we're now getting $30m. Sport is saying to us [your money] should be increased but they are not doing it in the same proportion. That probably is not a good way of addressing the issue."

WADA's estimation of the levels of cheating varies between sports, but Howman admitted his agency was catching just a fraction of those suspected of doping.

He added that the riches on offer in elite sport were tempting "vulnerable" young athletes and their coaches to dope early on in their careers, with drugs testing in non-elite events more limited than in senior competitions.

"We have some guestimates based on some research undertaken over the last years," Howman said of the number of athletes using performance-enhancing drugs. "It's far more than we would wish it to be - over 10 percent. That is of concern because those being caught by the system is far lower than that. Not in all sports, in some sports.

"The area of most concern for us is the level of young athletes who have not broken through into the elite who are trying to get that breakthrough and are susceptible to taking drugs because that's a shortcut.

"Not only are they susceptible to taking drugs, they are being encouraged to do so by any one of a number of people that surround them - coaches, trainers, even parents - because it's a way to make a lot of money."

Britain's double-Olympic champion Mo Farah, who will compete this weekend at London's Anniversary Games, has recently seen his coach Alberto Salazar and training partner Galen Rupp accused of doping, with claims Rupp was given a banned substance as a teenager.

Salazar and Rupp both deny the allegations, and there has been no suggestion of any wrongdoing by Farah; the world's fastest man, Usain Bolt, even said he felt sorry for the Briton following the furore surrounding his team.

Bolt, who is also set to compete in London's Olympic Stadium on Friday night, was firmer with his words for rival sprinters such as Tyson Gay and Justin Gatlin, both of whom have returned to the sport after serving drugs bans. Speculation over doping, he said, "doesn't help the sport" and left him "frustrated and angry".