The International Biathlon Uion (IBU) confirmed that Iourieva and teammates Albina Akhatova and Dmitri Yaroshenko had all tested positive for unspecified substances.

 

IBU president Anders Besseberg said: "We are facing systematic doping on a large scale in one of the strongest teams of the world."

 

Russian athletes were accused of "systematic planned doping" by Arne Ljungqvist, the Swede who is chairman of the International Olympic Committee's (IOC) Medical Commission and also a vice-president of the World Anti-Doping Agency (WADA), on the eve of the Beijing Olympics last August after seven female runners and throwers were banned for manipulating urine samples.

 

The tests on the biathletes were conducted at a World Cup event in Ostersund, Sweden, last December.

 

The three athletes have been provisionally suspended and will face an IBU disciplinary panel once the federation receives full results from a WADA-accredited laboratory in Lausanne.

 

The athletes risk two-year bans that could rule them out of the 2010 Winter Olympics in Vancouver .

 

Besseberg said: "Either we have been able to catch them all, or we have only seen the top of the ice mountain.

 

"There is no, absolutely no, excuse for what the three doped Russian athletes and the people behind them have done."

 

The Russian Biathlon Union said it would conduct its own investigation.

 

The confirmation came as athletes prepare to compete in the first biathlon World Championships to be held in Asia in Pyeongchang, who are bidding to host the 2018 Winter Olympics.

 

Iourieva leads the World Cup standings with 567 points halfway through the season.

 

She won gold in the 15-kilometer individual race at last year's worlds in Ostersund.

 

Since the positive test in December, Iourieva has won the 7.5-kilometer sprint and the 12.5-kilometre mass start.

 

Akhatova, a three-time world champion in mass start and relay, is sixth in the standings with 443 points. Yaroshenko is 21st in the men's field with 203 points.

 

He competed twice on Russia 's world champion relay team.