(CNN) A European court has ruled that Russia's so-called "gay propaganda law" is discriminatory, promotes homophobia and violates the European Convention on Human Rights.
The law bans "propaganda of non-traditional sexual relations around minors" and was justified by Russia's Duma as a necessary measure to protect children from homosexual influence.
On Tuesday the European Court of Human Rights in Strasbourg, France found that three gay Russian activists were discriminated against and their right to freedom of expression violated when they were fined for protesting against the law.
Nikolay Bayev, Aleksey Kiselev and Nikolay Alekseyev staged protests between 2009 and 2012, holding banners stating that homosexuality is natural and normal, and not a perversion, according to the court ruling. The activists had appealed to higher Russian courts without success.
Russia's Justice Ministry denied the law was discriminatory or that it restricted freedom of speech, and said it would appeal the ruling within three months, state-run media TASS reported.
The law is just one of many that the Duma has passed in the name of upholding what it sees as traditional family values. In January, it decriminalized some cases of domestic violence as part of this drive.
It also comes amid allegations of a brutal crackdown on gay men in the Russian republic of Chechnya. Witnesses have told CNN that hundreds of gay men have been held and abused in detention centers because of their sexual orientation. In April a Chechen government spokesman called the allegations of a crackdown "an absolute lie," and denied that gay men exist in the republic.
The law considered by the European court was first passed in the country's regions but became national legislation in 2013.
The court found that the law "served no legitimate public interest," rejecting suggestions that public debate on LGBT issues could influence children to become homosexual, or that it threatened public morals.
"Above all, by adopting such laws the court found that the authorities had reinforced stigma and prejudice and encouraged homophobia, which was incompatible with the values -- of equality, pluralism and tolerance -- of a democratic society," the court document said.
After the ruling was announced, TASS reported that the Justice Ministry disagreed with it, saying: "The relevant acts did not establish any measures aimed at banning homosexuality or its official censure, did not contain any signs of discrimination and, in its general sense, did not allow excessive action by public authorities."
The court decided by six votes to one that Russia must pay around 49,000 euros in damages and legal fees to the three activists.
The court in Strasbourg is responsible for the European Convention on Human Rights, which applies to all 47 members of the Council of Europe, including Russia.
But President Vladimir Putin in December 2015 signed a law that allows Russia's Constitutional Court to decide whether or not to implement rulings by international courts.