A gay rights activist said the celebration would be held in the village of Yablonevy, near the town of Novoulyanovsk, which has a population of seven people.
Nikolay Alexeev wrote on Facebook to say he had received a letter saying the event could take place outside the town.
Mr Alexeev said the mayor of the town, Svetlana Kosarinova, was “the bravest person in Russia” for approving the demonstration.
He said the event would take place on 26 August and warned that the authorised number of attendees, 300, should not be exceeded.
The activist said it was “the most awesome event in Russia’s history!” and called Ms Kosarinova ”a real liberal, democrat, and simply the greatest human.”
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