"The IBU Anti-Doping Hearing panel will decide about the period of ineligibility for both athletes," the body said on their official website.
Loginov, 22, who competed at the Winter Olympics in Sochi last year, tested positive for an unspecified banned substance on Nov. 25 and was expelled from the 2014-15 Biathlon World Cup.
Sednev, who last month announced his retirement, tested positive for banned substance EPO.
The 31-year-old won a bronze medal at the 2011 world championships.
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On Monday, the Ukrainian Biathlon federation (UBF) said in a statement it had questioned Sednev, who "was not able to explain or refute the use of illegal substances".
"The athlete was given the opportunity of opening the B sample. But as Sednev had finished his career after poor results over the past seasons, he decided not to conduct the further analysis," the UBF added on its official website.
(editing by Justin Palmer)
