"Aleksanyan, who is being held in hospital, has the right and the opportunity to take daily showers. His ward has a shower unit with hot and cold water supplies," spokesman Sergei Tsygankov told RIA Novosti.
Earlier reports had said Aleksanyan was banned from taking showers.
Vasily Aleksanyan, 36, has been diagnosed with AIDS and cancer. One of his lawyers who was admitted for a visit earlier in February said his client had told him he was normally kept chained to the bed.
"He is handcuffed to bed when there is no other way to secure him from an attempt to escape or commit suicide," Penitentiary Service spokesman Alexander Sidorov responded. "He is also handcuffed when he has visitors in his room, and when he leaves the room he is handcuffed to a guard."
The decision to move Aleksanyan, 36, from jail to hospital was made following demands from lawyers and former colleagues.
The former Yukos executive has been accused of embezzling about $330 million from former Yukos production unit Tomskneft and shares worth $493 million from other oil companies, as well as of laundering stolen assets,
Genri Reznik, a lawyer for Aleksanyan, said his defendant was satisfied with the hospital where he was being held. "As we were told... this hospital is the only one in Moscow which can provide treatment for the conditions Aleksanyan is suffering from," the lawyer said.
The prosecution earlier insisted he should undergo medical treatment in jail. However, a Moscow court suspended Aleksanyan's trial due to his worsening health.
Jailed ex-Yukos CEO Khodorkovsky, the founder of what was once Russia's largest oil producer, declared a hunger strike on January 30 demanding medical treatment for Aleksanyan. He called off his protest some two weeks later when Aleksanyan was admitted to hospital.
Aleksanyan earlier claimed that that the reluctance of the Russian authorities to provide him with medical treatment was due to his refusal to assist prosecutors with new charges against Khodorkovsky.
Yukos collapsed after claims of tax evasion in 2004 which led to the company being broken up and sold off to meet creditor claims. The bulk of its assets were bought through liquidation auctions by government-controlled oil company Rosneft. Yukos was officially dissolved in 2007.