Russia has experienced an upsurge in homophobic vigilantism following the introduction of legislation outlawing "homosexual propaganda" in June, gay and lesbian groups say.

The new laws, which have cast a shadow over the Winter Olympics to be held in Sochi early next year, ban the promotion of "non-traditional sexual relations" among minors.

Activists say the legislation has emboldened rightwing groups who use social media to "ambush" gay people, luring them to meetings and then humiliating them on camera – sometimes pouring urine on them. These groups often act against gay teenagers, several of whom told the Guardian that rising homophobia and vigilante activity force them to lead lives of secrecy.

The Russian LGBT Network said the harassment of gay people was being organised nationally for the first time through groups known as Occupy Gerontophilia and Occupy Paedophilia, who claim to be trying to "reform" homosexuals.

Igor Kochetkov, the head of the network, said Occupy Paedophilia – which focuses on gay adults – had uploaded hundreds of videos and garnered hundreds of thousands views on social media sites. Occupy Gerontophilia, which focuses on teenagers, had uploaded dozens of videos to the social network VKontakte before its page, which had 170,000 subscribers, was shut down for invading the privacy of minors.

"The latest laws against so-called gay propaganda, first in the regions and then on the federal level, have essentially legalised violence against LGBT people, because these groups of hooligans justify their actions with these laws," Kochetkov said. "With this legislation, the government said that, yes, gays and lesbians are not valued as a social group.

"It is an action to terrorise the entire LGBT community," he added.

Kochetkov said most homophobic violence was not reported to the police, but a recent study by his organisation found that of 20 attacks that had been reported recently, four were investigated and only one resulted in a court case. Russian law did not outlaw discrimination based on sexual orientation, he said.

One gay teenager, Robert, who lives in the Siberian city of Kemerovo, said he narrowly avoided exposure at the hands of Occupy Gerontophilia.

"They tried to trick me into a meeting but I immediately saw the ruse," Robert said, recounting an online chat, supposedly with a 22-year-old man, who had offered him money to meet up. After being confronted, the man admitted he was from Occupy Gerontophilia, Robert said.

In a series of interviews with young homosexuals, the Guardian found that widespread fear means their relationships are nearly always clandestine and abuse is commonplace. As well as vigilante violence, they are also scared of negative reactions from family and friends. And if life in Moscow and St Petersburg is hard enough, then in the Russian provinces homosexuality is the love that dare not even whisper its name.

Recently an MP in the Siberian region of Zabaikalsk called for a law allowing gays to be publicly flogged by Cossacks.

Fifteen-year-old Robert said vigilante groups had expanded in his city following the new legislation. "In general, people's attitude here toward LGBT has worsened after long-running homophobic propaganda in the mass media," he said. "As soon as the hoopla started with the passage of the law, branches of organisations like Occupy Paedophilia and Occupy Gerontophilia appeared in our city."

Whereas the relatively cosmopolitan Moscow and St Petersburg have several gay clubs and bars – one of Moscow's best-known nightclubs, Propaganda, also hosts a gay party every Sunday night – other cities in Russia are generally more conservative. A poll in April found that 43% of Russians considered homosexuality to be "licentiousness, a bad habit" and 35% said it was an "illness or the result of psychological trauma".

Teenagers suffer the most from homophobia, and studies have found that LGBT youth commit suicide at much higher rates than their peers. People "scorn and hate lesbians, and hate and beat gays", said Lena, a 14-year-old from Abakan, a city of 170,000 in Siberia. She said an acquaintance had tried to trick her into going on a date with a girl. "It was a good thing my friend was able to talk me out of it, since I found out later that several homophobes were waiting for me there," she said.

Ruslan, a 17-year-old living in Tambov, where both Occupy Gerontophilia and Occupy Paedophilia have been particularly active, said he tried to "prepare a person" by talking about homosexuality in general before he told them about his sexual orientation. If they reacted negatively he wouldn't say anything. Most did, he said, adding that only his closest friends knew that he was gay.

"My parents are extremely conservative. If I tell them they will throw me out of the house," he said.

Marina, a 17-year-old who lives in the small city of Bronnitsy, in the Moscow region, said she tried to come out to her mother but "turned it into a joke" when she heard her mother's reaction. "I told her, 'I've fallen in love with a girl.' At first she said it was affection, not love, and then that I wouldn't be able to have children," Marina said. "Then I understood how limited her perception of same-sex couples is."

Artyom Reutov, a 15-year-old from the city of Veliky Ustyug, in the north of Russia, said his teachers were openly homophobic, suggesting that LGBT should be exiled or given compulsory medical treatment. "At the end of the last school year, I heard a ton of homophobic statements from teachers," Reutov said.

He hasn't come out to his conservative mother, who would prefer him to watch football rather than engage in his hobbies of drawing and singing. "If I was a bad student and hung out in the courtyard, drank and swore, it would be better [for her] than me being who I am now," he said.

The only public support is Deti-404, a group for LGBT teenagers that has pages on Facebook and VKontakte. Several times a day different users post photos, personal stories and statements of support. Several of the teenagers said the group had helped them come to terms with their orientation and find friends.

"I can go on [the Deti-404 site] and see that there are other teens with non-traditional orientations and people who wish me happiness and don't hate me," Lena said. "I write a lot. I can get all my emotions out and put them on the site, where people appreciate them."