In an email sent to supporters last week, the 34-year-old said he would no longer head Moscow Pride and GayRussia.ru but gave little reason for his decision.
In a Facebook post, he wrote:
Dear friends … today on 21 October 2011, one year anniversary of the European Court of Human Rights verdict in the case of illegality of Moscow Pride bans, I decided to resign from the positions of the head of Russian LGBT Human Rights Project GayRussia.ru and head of Moscow Pride Organizing Committee. From midnight 21 October 2011 in Moscow and up to the decision on the new leadership, Project GayRussia.ru will be headed by Nikolay Baev and Moscow Pride Organizing Committee by Alexander Naumchik.
Speaking to UKGayNews.org.uk, he added:
It is true that I am fed up, and that is why I decided to step down. I also decided not to give any further comments on my decision.
Mr Baev, who will take over GayRussia.ru, said:
The reason [for Alexeyev’s resignation] is totally personal. He just decided to change his activity and lifestyle, and he has a full right to this.
Alexeyev, a former journalist, turned his attention to full-time gay rights campaigning in 2005, setting up GayRussia.ru and making plans for a Pride march in Moscow.
He has appeared regularly on Russian television and has been honoured for his work by LGBT organisations worldwide.
He has been arrested on numerous occasions for holding illegal Pride marches and gay rights demonstrations and launched lawsuits against Moscow authorities for banning the events.
Last September, the campaigner was arrested at Domodedovo Airport in Moscow while boarding a plane to Geneva.
He says he was kidnapped and possibly drugged by Russian security forces who detained him for more than two days and used his phone to send fake messages claiming he was dropping his legal challenges.