MOSCOW (AP) — A prominent investigative journalist who was detained on drug-dealing charges in Russia is being taken to the hospital after complaining of feeling poorly in police custody.

The Moscow police department said Saturday that an emergency medical squad was called for Ivan Golunov and determined he should be taken a hospital for examination.

It did not specify Golunov's medical problem. The head of human rights organization Agora, Pavel Chikov, told Russian news agencies Golunov was suspected to have a concussion and a broken rib.

Golunov's publication, the independent website Meduza, said he allegedly was beaten after his Thursday arrest.

Police are alleging four grams of a synthetic stimulant were found in his backpack. But many journalists suspect the arrest was retribution for Golunov's investigative work.