Five gay rights activists have been detained in Moscow as they tried to deliver a petition to the office of Russia’s prosecutor general.
Police said they were held because their action was unauthorised.
The activists said more than two million people had signed the petition to investigate alleged torture and detentions of gay people in the Russian region of Chechnya.
Chechen officials have denied that gay people even exist in the republic.
Last week, Russian President Vladimir Putin backed an inquiry into the reported crackdown on gay people in Chechnya, in the North Caucasus.
Earlier this month German Chancellor Angela Merkel urged the Russian authorities to help protect gay rights.
On Thursday, four Russians and an Italian national were held as they tried to deliver a printout of the petition to the prosecutor general’s office.
They also carried huge empty boxes, symbolising online signatures they had collected in protest against the alleged crackdown, a BBC Russian reporter says.
The petition was signed “by more than two million people around the world, more than the entire population of the Chechen republic,” the Russian LGBT Network said.
It said they were demanding “an unbiased investigation of illegal detentions of hundreds of people in Chechnya because of their homosexuality”.
Chechnya’s strongman leader, Ramzan Kadyrov, said last week he was ready to co-operate with Russia’s federal authorities on the issue.
But Mr Kadyrov repeated recent assertions that there were no “people of non-traditional orientation” (a term sometimes used to describe LGBT people in Russia) in the predominantly Muslim republic.
Chechen officials also say the local police have not received any official complaints from alleged victims.