Moscow Gay Pride organiser and gay rights activist Nicolas Alexeyev will be questioned next week in relation to a criminal investigation after he outed a Russian MP on live television.

The charges arise from comments he made on live TV in June, when he outed politician Alexander Cheuv as a homosexual.

To prove that he is guilty of slander, Russian investigating authorities will have to demonstrate that calling Mr Chuev ‘gay’ spoilt his reputation or dignity.

Speaking on the talk show K baryeru! on 21st June Mr Alexeyev, who was convicted of a minor offence for his role in May’s banned Mosow Pride march, outed the conservative MP.

Mr Chuev is one of the most outspoken opponents of gay rights, and has introduced proposals to the Duma to outlaw the “promotion” of homosexuality and ban “gay propaganda.”

Mr Alexeyev claimed that Mr Chuev’s gay relationships were well-known in the 1990s before he became a politician, and called him a coward and a liar.

“We reached the most important thing during this TV show,” Mr Alexeyev said at the time of his TV outburst.

“We showed all hypocrisy of the representatives of the present Russian authorities.

“They have secret homosexual relationships but at the same time they do all their best in order to slander gays and lesbians.

“I am ready to prove at any court or prosecution office that deputy Chuev is gay and to produce corresponding proofs.”

It was the first time a politician had been outed in Russia.

Mr Alexeyev said that by charging him with slander, the authorities were “caught in their own trap.”

“On the one hand they are saying all the time that no-one is discriminating gays in Russia and that there is no problem being gay and on the other hand they are investigating whether the word ‘gay’ can be insulting.

“Obviously not, because homosexual relations are not anymore prosecuted in Russia and homosexuality is not classified as a mental illness.”

He added that the criminal investigation is an attempt to intimidate him into dropping a series of legal actions he is bringing against the Russian authorities in the European Court of Human Rights.

“It is clearly one other example of Russia becoming an authoritarian state where people do not have any right to express themselves and speak freely. And Russian authorities particularly do not like those who reveal bitter truth about them.”

The Russian media have tried to link Moscow Pride with the exiled billionaire Boris Berezovsky, with reports he was planning to give $100m (£50m) to finance gay Pride events throughout Russia.