Biathletes who submitted positive doping tests at the World Cup season-opener in December have requested the examination of the b-sample, the ruling body IBU said on Wednesday, dpa reported.
IBU secretary general Nicole Resch made the announcement in a telephone interview to Deutsche Presse-Agentur dpa, saying the examination would tale place "as soon as possible" which will likely be before the world championships starting February 13.
The IBU has neither released the names nor the substance due to the ongoing process, saying only that an examination is taking place after a-tests returned positive.
Russian sports minister Russian sports minister Vitali Mutko and other officials have acknowledged that athletes from his country are involved.
Russian daily Komsomolskaya Pravda on Wednesday named the three athletes, saying that World Cup leader and world champion Eketarina Iourieva, three-time world champion Albina Akhatova as well as two-time relay world champion Dmitri Yaroshenko were the suspects.
The paper cited unofficial sources in its report.
The athletes were allegedly caught blood doping with a new substance (not EPO or its third generation known as CERA) in target tests at the World Cup opener in Ostersund, Sweden, Russian media said.
Iourieva won 15km gold, pursuit silver and mass start bronze at the 2008 worlds, and is the current World Cup leader. Akhatova won the 2003 mass start world title and also has relay golds from the 2000 and 2003 worlds and 2006 Olympics. Yaroshenko is also a two-time relay world champion, from 2007 and 2008.
Resch's statement underlines that the IBU wants to solve the case before the February 13-22 world championships in Pyeongchang, South Korea.
If the b-test confirms the original finding the athletes can be suspended and eventually face a two-year-ban from competition if found guilty of doping.
The Russian team reportedly departed for South Korea on Monday.