"The Embassy is not aware of the name, type and regime of the prison to which our compatriot is planned to be transferred," Antonov said in the statement on Friday. "Taking into account the pre-existing conditions that Konstantin Yaroshenko has, we believe that changing the place of serving his sentence may negatively affect his physical and mental state of health. In this regard, at the request of the relatives of the Russian citizen, we sent a diplomatic note to the US Department of State with a request not to change the place of detention of Konstantin Yaroshenko."
Antonov said the Embassy does not know the name or the type of prison it is that Yaroshenko will be sent to by US authorities.
Earlier on Friday, Yaroshenko's legal defense asked US authorities to revise the decision on his relocation to a private prison.
Yaroshenko is currently jailed at the Danbury correctional facility in the state US state of Connecticut.
Yaroshenko was arrested in Liberia in May 2010 on suspicion of drug trafficking. A year later, he was extradited to the United States and sentenced to 20 years in prison for allegedly taking part in a conspiracy to smuggle a large amount of drugs to the country. He has denied all charges.