Anti-gay activists led by a city lawmaker have disrupted a gay rights festival in the Russian city of St. Petersburg, dousing participants with green liquid and releasing a gas that made many feel sick.

St. Petersburg lawmaker Vitaly Milonov, his aide Anatoly Artyukh, and activists who associate themselves with the Russian Orthodox faith interrupted the opening ceremony of the "KviroFest-2014" event at a cafe on September 18.

The visitors splashed an indelible green antiseptic on participants and released an unidentified gas that sickened many..

The 10-day festival opened despite the attack.

Russia decriminalized homosexual relations after the 1991 Soviet collapse, but such harassment is common.

Rights defenders and Western governments including the United States say a 2013 law  banning the dissemination of gay "propaganda" to minors is discriminatory and encourages ill-treatment of LGBT people.