Professional computer gaming is growing at such a rapid rate that there are calls for more regulation to prevent match-fixing and doping.

Annual e-sports prize money has jumped from £23m in 2014 to an estimated £36m this year, with professional e-gamers earning six figures or more a year.

They have agents, nutritionists, train up to 10 hours a day and are treated like celebrities by supporters who follow them around the globe.

With millions of pounds at stake, the pressure to perform has led to temptation to dope.

Sports Lawyer Andrew Nixon told Sky Sports News HQ: "There have been one or two cases around the world, especially in relation to cognitive enhancement drugs.

"The international federation is endeavouring to deal with it but like all of these things it requires resources and it needs to be policed and properly sanctioned."

He says that whilst the International e-sports Federation is tackling the problem, there is still a disparity in how the leagues and competitions are governed.

He was speaking at an e-sports event at the Queen Elizabeth Olympic Park in London - attended by 4,000 fans.

Events around the world are attracting tens of thousands of supporters, who are also watching online, while NewZoo estimates there are 1.7bn gamers worldwide and 56% of fans are aged 21-35.

Danish player Nicolai Reedtz, 20, had a different career planned until he realised gaming could make him a millionaire.

"I was actually going to law school this month but I decided to take the step into full-time gaming and I have high expectations," he said.

"I think it's growing a lot more like football. My parents were sceptical but as they see it growing and see money coming in, they actually now support me."

Some competitors believe that e-sports should fight to be recognised as an official sport but even those involved can't agree on its status.

Professional e-gamer Nathan Schmitt, 21, says: "It's a very hard question. Even this community is divided. Three quarters think it should be considered a sport but I think it should be considered an e-sport, not an actual sport.

"It's not physical, but it's very special."