A Russian journalist known for investigating corruption among Moscow city officials has been detained by police and accused of drug offences, the police said on Friday, but his lawyer and employer said he had 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 rucksack, according to police and his employer, the online news portal Meduza.

In a statement, Moscow police said a search of Golunov’s apartment had produced more drugs and some scales, and that they had opened a criminal investigation. If found guilty of large-scale drug selling, he could be jailed for 10 to 20 years.

Dmitry Djulai, Golunov’s lawyer, told Reuters that 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 rucksack or to take fingernail samples to see if he had been in contact with drugs.

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.

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.”

Djulai said the police had also refused to call medics to catalogue the injuries that police had inflicted.

Moscow police said the allegations that Golunov had been beaten as he was arrested “do not correspond to reality”.