MOSCOW (AP) A Russian bobsledder who won a gold medal at the 2014 Olympics has been banned for four years for doping.

The Russian Anti-Doping Agency said Tuesday that Dmitry Trunenkov, who won the four-man bobsled at the Sochi Games, tested positive last year and has been banned by the Russian Bobsled Federation.

Neither organization specified what substance Trunenkov tested positive for. The ban won't affect his Olympic gold medal.

''We are very disappointed,'' RBF president Alexander Zubkov, who was Trunenkov's teammate at the 2014 Olympics, said in comments to state news agency Tass. ''We will look into how this happened.''

Trunenkov's ban is backdated to April 2016, four months before he retired from competition to focus on his role leading a patriotic youth group set up by the Russian armed forces.

The inquiry into Trunenkov was separate from ongoing investigations into allegations of widespread, state-sponsored doping by Russia at the 2014 Sochi Olympics.

RUSADA also announced a four-year ban for race walker Alexander Yargunkin, who tested positive shortly before he was due to represent Russia at the 2015 world track championships. Also, rower Yulia Solomentseva, who won silver at the 2014 world junior championships, was given a one-year sanction after being found guilty of failing to make herself available for testing.