A man whose lawyer says he accidentally stumbled on information about pro-Ukrainian combat units while browsing the internet on a bus is the first Russian known to be investigated under a law banning online searches for material Moscow calls extremist.

Russian media quoted Sergei Barsukov, a lawyer in the Sverdlovsk region of the Urals, as saying he was representing 20-year-old Sergei Glukhikh, who had been reported by his internet service provider to the FSB security service for viewing information about units Russia regards as terrorists.

The news outlet Ostorozhno Novosti quoted Barsukov as saying his client had no malicious intent, and complaining that investigators had exerted psychological pressure on him.

Russia has introduced censorship laws since its 2022 invasion of Ukraine that make people liable to fines or long prison sentences if they “discredit” the Russian armed forces or spread “knowingly false information” about the war.

A new law passed in July sets fines of up to 5,000 roubles ($61.50) for people who knowingly search for extremist materials online. Although the fine is small, critics say the move could be used as a pretext to place people under investigation and open the door to more serious charges and penalties.

Barsukov, the lawyer, said no judgement had yet been reached in his client’s case, but a lot of people would suffer unfairly as a result of the legislation.

“Imagine I’m a researcher and I’m preparing an article about banned organisations. And it turns out that I’m defenceless – an (internet) operator reports me to law enforcement,” he was quoted as saying.

“It’s time to stop this farce and stop dragging decent citizens through the courts.”