MOSCOW — The police in Moscow on Friday announced the detention of an investigative journalist on drug charges, in what appeared to be the latest official effort to muzzle independent voices in Russia.

Ivan Golunov, 36, a reporter who has specialized in exposing corruption in Moscow City Hall, was detained on Thursday on his way to meet a fellow reporter. Mr. Golunov works for Meduza, an online news service.

On Saturday, the Moscow police formally charged him with attempting to sell a “large amount” of drugs including mephedrone, a recreational drug and cocaine, Pavel Chikov, the head of Agora, the nongovernmental organization providing his legal representation, wrote on Telegram.

Mr. Chikov posted a copy of the official documents and said that his client was possibly suffering from a concussion but that the police were resisting taking Mr. Golunov for medical treatment. Mr. Golunov was later hospitalized, the police and Meduza announced on Saturday.