Russia's top court has stated that the country's controversial "gay propaganda law" is constitutional, dismissing a complaint from a prominent gay rights campaigner.

Nikolai Alexeyev was fined by a city court in St Petersburg for holding up a banner with a quote by a renowned Soviet-era actress Fain Ranevskaya which stated: "Homosexuality is not a perversion, unlike grass hockey or ice ballet."

Alexeyev, who is the founder of the Moscow Gay Pride Movement, filed a lawsuit to the constitutional court claiming the law was based on prejudice and that it allowed discrimination against people based on their sexual orientation, according to RIA Novosti.

The city's statute imposes fines of up to 5,000 rubles (£92) on individuals judged to promote homosexuality among minors. A similar federal bill was approved by the State Duma in June and signed into law by president Vladimir Putin.

The state legislation, harshly criticised by human rights activists in Russia and abroad, outlaws the "propaganda of nontraditional sexual relations to minors".

In response to Alexeyev's appeal Russia's high court said the state reserves the right "to protect motherhood, childhood and family".

Legislators have a duty to "take measure to protect children from information, propaganda and campaigns that can harm their health and moral and spiritual development," it said.

The court's ruling was made on 24 October but only released on 4 December.

In a separate case, Alexeyev and another LGBT activist were found guilty of promoting "non-traditional" relationships to minors and fined each 4,000 rubles (£73).

They were on trial for picketing in front of a children's library holding banners that read: "Gay propaganda doesn't exist. People don't become gay, people are born gay."

"These are the first court decisions in Russia's history to prosecute for propaganda of non-traditional sexual relationships under the new federal law," Alexeyev told GayRussia.