According to the yearly report by the Sova Centre, which specializes in studying xenophobia, 228 people were convicted under the "extremist propaganda" law in Russia last year -- up from 220 people in 2016 -- and 47 were given jail sentences.
Almost all convictions related to pictures, videos or messages posted online, the NGO said, adding it was possible the law was a pretext to enforce "political repression".
"The fight against extremism is growing, restricting freedom of speech. These restrictions are often applied too widely," it said in a statement.
Sova said that the list of banned "extremist" publications was updated 33 times over the course of the last year.
The list includes historical and opposition publications.
Last August a Russian court jailed an investigative journalist for three and a half years, in a case denounced by media rights activists.
Alexander Sokolov was arrested on suspicion of participating in a banned extremist group.
He denied wrongdoing, saying his prosecution was instead over an investigative report published two weeks earlier on government overspending on a project to build a new space port.