Athletes have gathered in Las Vegas for the first-ever Enhanced Games, where organisers predict world records will be toppled by competitors using performance-enhancing drugs.

Around 40 sprinters, swimmers and weightlifters have spent the past four months in Abu Dhabi taking combinations of testosterone, human growth hormone, peptides and anabolic steroids - all banned by events like the Olympics.

The event has been denounced by athletics governing bodies and anti-doping agencies as dangerous and against the spirit of sport.

But participants, lured by prize money of up to US$1 million ($1.7m) for beating world records, will include Olympic medallist swimmers James Magnussen, Cody Miller and Ben Proud, who have all taken drugs.

Hafthor “Thor” Bjornsson, best known for playing The Mountain in Game of Thrones, will try to break his own deadlift record.

Former 100m sprint champion Fred Kerley will be one of the few athletes competing without drugs at the event.

Max Martin, chief executive officer and co-founder, has predicted multiple world records will be “beaten”, though the feats will not be officially recognised.

Weightlifters Beatriz Piron and Arley Mendez surpassed world records in training, he told a press conference on the eve of the event.

Martin said: “Hopefully they’ll be able to do it tomorrow as well, and then we’ll see a few more. My guess is we’ll see quite a few.”

Swimmers will also be allowed to wear the types of “supersuits” that led to many world records falling around the 2008 Beijing Olympics but were subsequently prohibited.

Chief sporting officer Rick Adams said he respected that “specific international organisations” would not accept any records set on Sunday, even if they were broken by clean athletes like Kerley.

The Enhanced Games are taking place at a purpose-built US$50m arena in a Las Vegas casino parking lot, a structure to be dismantled hours after the final race.

In a marriage of sports, biohacking, politics and entertainment, investors including billionaire Peter Thiel are rumoured to be attending, while rock band The Killers will play a closing set. Donald Trump jnr is among the event’s investors.

- AFP