A legislator in the Russian city of St Petersburg has said he will seek to annul a marriage between two women, one of whom was born male.
Vitaly Milonov, an opponent of gay rights, said the wedding on Saturday was an "insult" to Russian families.
Gay marriage is banned in Russia, but the couple were not denied a ceremony because according to their passports one is a man, the other a woman.
It is unclear whether this was Russia's first case of such a union.
A controversial 2013 law on "anti-gay propaganda", makes it illegal to distribute information about homosexuality to children in Russia.
Correspondents say the law comes as part of a campaign for "traditional values", with members of the lesbian, gay, bisexual and transgender (LGBT) community feeling increasingly threatened.
http://www.bbc.com/news/world-europe-29975477
