A Russian journalist known for investigating corruption among Moscow city officials has been charged with large-scale drug trafficking, but his lawyer, his employer and colleagues say he has been framed.

The journalist, 36-year-old Ivan Golunov, was detained in central Moscow on Thursday on his way to a meeting with a source when illegal drugs were found in his backpack, according to police and his employer, the Meduza news website. Golunov denied that the bag belongs to him.

Golunov was charged with large-scale drug selling on Saturday, Meduza reported. If found guilty, he could be jailed for 10 to 20 years.

Meduza reported on Saturday that doctors said Golunov may have sustained broken ribs, a concussion and a hematoma during his detention.

Russian news agencies cited police as saying that Golunov had been taken to hospital.

Meduza reported later on Saturday that the journalist had been released from hospital and taken back to court after doctors ruled out a head injury.

The court said it had received a request from investigators to hold Golunov in custody on drug charges. He could either be placed under arrest in custody, subject to house arrest, released on bail, or released with travel restrictions.

The court may also extend his detention by 72 hours.

Dmitry Dzhulai, Golunov’s lawyer, told Meduza he believed police had planted the drugs on his client to frame him. He said Golunov had been beaten, and that police had refused to take swabs from his hands or the backpack, or fingernail samples to see if he had been in contact with drugs.

Dzhulai said the police had also refused to call medics to document the injuries he said police had inflicted. Moscow police said the allegations that Golunov had been beaten as he was arrested “do not correspond to reality.”

In a statement Friday, Moscow police said they had found more drugs and some scales in a search of his apartment, and that they had opened a criminal investigation.

Russia’s Interior Ministry on Friday published nine photos, which were later deleted, that it described as showing narcotic substances found in Golunov’s apartment. The ministry denied reports that Golunov had been beaten after his detention. Meduza said only one of the photos was taken at Golunov’s apartment and that handwriting shown in the photos doesn’t match Golunov’s handwriting.

Golunov is well-known in Russia for his investigations into graft in the capital. Moscow Mayor Sergei Sobyanin is a close ally of President Vladimir Putin.

Sobyanin on Friday ordered the head of Moscow’s police force to take the investigation under his personal control and to ensure the matter was dealt with objectively, Russian news agencies reported.

The editorial management of Meduza, which is based in Latvia, said in a statement that Golunov had received threats in recent months in connection with a story he was working on.

“We are convinced that Ivan Golunov is innocent,” the statement read. “Moreover, we have grounds to believe that Golunov is being persecuted because of his journalistic activity.”

Dozens of people protested against Golunov’s detention outside Moscow police headquarters on Friday. Police detained up to 20 of them before later letting them go.

A long line of journalists was nonetheless waiting to take turns to stage one-person protests, the only form of legal protest in Russia which does not require prior permission from the authorities.

Reuters contributed reporting to this article.