The founder of an online community for LGBT teenagers in Russia has been fined under the country’s law against gay propaganda.

Elena Klimova was fined 50,000 roubles (£540) after a court in Nizhny Tagil concluded that Deti-404, which has pages on Facebook and Russian social network VK, was guilty of distributing “propaganda of non-traditional sexual relations among minors”. Klimova said she would appeal against the ruling.

Kilmova successfully appealed against a fine levied by a court in the same town in January.

With parents and teachers often unsympathetic or even hostile, Deti-404 (Children-404) is one of the few platforms for Russian teenagers to discuss LGBT issues in a safe space. Nearly every day, young people write in with stories and photographs – with their faces and names often hidden – describing the harassment, beatings and confusion they suffer due to their sexuality.

The group has recently come under attack by the authorities and pro-Kremlin activists. At the request of the local prosecutor general’s office, a court in St Petersburg in March found Deti-404 guilty of gay propaganda and ruled that its VK page should be blacklisted. The court said it would have the state communications watchdog block the page, but it has remained accessible. Klimova said she also intends to appeal against this ruling.

Putin signed the law against gay propaganda in June 2013. Later that year, gay rights campaigner Nikolai Alexeyev and fellow activist Yaroslav Yevtushenko became the first people to be fined under the law after they stood outside a library in Arkhangelsk with banners that said: “Gay propaganda does not exist. People do not become gay, people are born gay.”

A newspaper editor in Khabarovsk was also fined under the law after he ran an article about gay rights activist Alexander Yermoshkin, who said he had been assaulted and forced to quit his job because of his sexuality.

Activists have said the legislation has resulted in increased harassment and violence against LGBT people, especially teenagers.

“The law against gay propaganda legitimised violence against LGBT people, and they now are banning street actions under it,” Klimova said. “People are afraid because they understand that gay propaganda is banned, and even mentioning LGBT relations is essentially forbidden.”

Klimova herself has been the subject of vituperative online commentary after creating Deti-404 in spring 2013. In April, she published a photo album on her social media page called “Beautiful People and What They Say to Me,” where she paired users’ profile pictures with threatening, expletive-laced messages they had sent her. “Go and fucking kill yourself before before they come for you,” wrote a woman pictured smiling with a bouquet of roses in her profile picture. “Gunning you down, you little bitch, is just the beginning of what you deserve,” wrote a man pictured alongside a baby goat.

Earlier this month, Yermoshkin left Russia following a state television broadcast that claimed to show US intelligence agents recruiting him to hold LGBT rallies in Russia. The activist said the conversation with the supposed intelligence agents was a setup and he cooperated out of concern for his safety.