A gay rights activist who staged a one-man protest against Russian anti-gay laws earlier this month, may be charged with extremist activity, a government official said on Wednesday.

A video was posted online of lone gay rights activist, Kirill Kalugin, being assaulted by a violent group of Russian paratroopers in the city that was the birth place of the country’s anti-gay legislation.

Kalugin was holding a rainbow banner in St Petersburg that read: “This is propagating tolerance” when he was attacked.

St Petersburg state official Vitaly Milonov, who co-authored the law which bans the “promotion” of homosexuality to minors originally adopted in St Petersburg, and other areas, before becoming a federal law in June, said another poster held up by Kalugin which read “Sodom in every home”, constituted extremist behaviour.

“He either mentally ill, or is paid [for his activity]. I’m afraid it’s both,” said Milonov, continuing to say that the activist had used the poster at several rallies, and had posted it online.

Milonov said that Kalugin was at the scrutiny of the authorities, and that chargers were being prepared against him.

Kalugin had said he does not consider his activities to be extremist, but that he had intended to encourage the free spread of information about LGBT issues in Russia. He said he would not seek political asylum in another country, and that he was not frightened by Milonov’s statement.

President Vladimir Putin signed the law in June banning the promotion of “non-traditional relationships” toward minors, a move that has been criticised as part of a broader crackdown on Russia’s gay community. Other laws banning the adoption of Russian children by foreign same-sex couples, and one which enables organisations receiving funding from abroad to be fined as “foreign agents”, were also passed.

The laws have so far sparked controversy among LGBT activists, with some calling for a boycott of the 2014 Sochi Winter Olympics. Others have also called to boycott Russian vodka as a form of protest.

On Monday, the Russian Interior Ministry confirmed that recently introduced anti-gay legislation will remain in force during the Sochi games.

A petition which has gathered over 150,000 signatures, calls for the 2014 games to be relocated to Vancouver, following the passage of anti-gay laws in Russia.

In an interview last week, a senior International Olympics Committee member said: “Russia must respect the Olympic Charter, or we will say goodbye to them”, broaching the question of relocating the games with the IOC for the first time.