“They even deny they exist and deny the problem exists,” Andrei Potapov, one of the protesters, told Euronews of Chechen officials. A spokesman for the regional leader, Ramzan A. Kadyrov, told The New York Times this month that Chechnya had no gay men.
It was not immediately clear why the police had detained the activists. Among them was Igor Kochetkov, director of the Russian LGBT Network, a group that has been providing gay men from Chechnya with safe houses elsewhere in Russia.
Tens of thousands of people in Russia attend May Day parades, which are intended to highlight labor issues and defend the rights of workers. In Moscow, Gennady A. Zyuganov, the leader of the Russian Communist Party, gave a speech in front of a poster of Joseph Stalin.
Fontanka, a St. Petersburg news portal, reported that the police had detained 18 people under a law against “violations by participants of a public activity of the rules of its implementation.”
That implied that the gay rights message had not been approved for the pro-labor marches, though the Fontanka report did not say precisely how the protesters had violated the parade rules.
Videos posted online showed activists carrying rainbow flags, and then police officers bundling some of them into a van. Reached by cellphone in jail, Mr. Kochetkov said about 20 people had been arrested, Reuters reported.
The Russian LGBT Network, Mr. Kochetkov’s group, has created an emergency volunteer network to help gay men escape Chechnya, operating a hotline and safe houses.
Even by the standards of Chechnya, a small region tormented by two brutal wars for independence in the post-Soviet period, the mass arrests of gay men seem brazen.
To counteract popular support for an Islamist insurgency that erupted after the Soviet breakup, President Vladimir V. Putin of Russia has granted wide latitude to the regional leader, Mr. Kadyrov, to co-opt elements of the Islamist agenda, including an intolerance of gays. Local officials in Chechnya and federal officials in Moscow have denied that gay men are being abused.
“You should ask those devils to apologize and kneel before the Chechen people for insults, humiliation and accusation,” Mr. Kadyrov told RBK television last month, speaking of Russian journalists who have documented the arrests and abuse of gay men.
“The best way to lead a healthy lifestyle is to have the right orientation,” he said. “God created us men, women and animals. Have you seen any religious pronouncement that would say you should marry a cat, for example?”
Earlier this year, to find closeted gay men, the authorities began to pose on social networking sites as gay men looking for dates and detained the people who responded, according to Chechen gay men interviewed last month.
Novaya Gazeta, a Russian independent newspaper, reported that more than 100 gay men had been arrested and that at least three had died. Human Rights Watch has corroborated that conclusion based on its own interviews with victims.