Pyeongchang, South Korea - Three Russian stars have failed doping tests and the world championship opening ceremony fell victim to bad weather on a black Friday for the sport of biathlon.

The International Biathlon Union (IBU) said that Ekaterina Iourieva and Dmitri Yaroshenko each failed two tests at the World Cup season-opener in Ostersund, Sweden, in early December. Albina Akhatova submitted one positive sample there as IBU boss Anders Besseberg spoke of organized doping.

The IBU said it will now launch the necessary disciplinary proceedings. It did not name the substance but is is reportedly a new generation of the blood booster EPO.

Besseberg did not want to comment on sanctions for the Russian team while the athletes, who have already left South Korea for Moscow, face a two-year ban if found guilty.

"Unlike previous doping cases we are now facing systematic doping on a large scale in one of the strongest teams of the world," said Besseberg.

"Is that all or just the tip of the iceberg?" asked Besseberg, promising a major effort to identify everyone involved in the scheme.

Iourieva is the reigning 15km world champion and women's World Cup leader; Akhatova has a mass start world title, three relay golds from worlds and Olympics and a team event world title; and Yaroshenko has two relay world titles.

Several teams were reportedly debating a boycott of the season-ending World Cup events March 26-29 at the Russian venue of Khanty-Mansiysk in protest at the affair.

It is the latest blow for the Russian biathlon team which at the 2006 Olympics in Turin had Olga Pyleva disqualified for using a forbidden substance after originally getting silver in the 15km event.

The absence of the three stars will heavily dent its medal ambitions at the first world championships on Asian soil which got off to a bad start Friday when heavy rain forced organizers to cancel the opening ceremony of the event which runs until February 22.

But organizers remained upbeat that the slopes will allow the opening sprint races for men and women to go ahead as planned on Saturday.

"The situation is critical, but the weather forecast makes me optimistic that we can prepare the slopes in such a way to have a fair competition," said IBU technical delegate Norbert Baier. (dpa)