A Russian lawmaker, who has strongly backed anti-gay legislation, said Facebook should be shut down in Russia over its support for the US Supreme Court's decision to legalise same-sex marriage.

Lawmaker Vitaly Milonov said he would formally request Russia's telecoms oversight agency to shut down Facebook which has introduced a function allowing users to decorate their profiles with the rainbow flag of the gay rights movement.

"It is a crude violation of Russian legislation. Facebook has no age limits, it is impossible to control how many minors are there," Saint Petersburg lawmaker Milonov said on Russian radio Saturday evening.

"That is why it would be completely normal to pull the plug on Facebook in Russia."

Milonov, who sits in the regional parliament of Saint Petersburg, introduced a law in the city banning "propaganda" of gay relationships to minors before a similar federal law was adopted and came into force in 2013, sparking international controversy.

Milonov said he would petition Roskomnadzor, Russia's telecoms oversight agency, and if that does not help he would appeal to the FSB security service and President Vladimir Putin personally.

"I would call on thousands of people and we will write to the FSB and Putin," he said.

"Any normal person would not leave this unnoticed. If Roskomnadzor does then they play on the side of those who whish harm to our homeland."

In a show of support for the US Supreme Court's historic decision, many Russians added a rainbow filter to their Facebook profile photos.

Milonov's words drew disdain from activists, and a picture of Milonov superimposed against the rainbow flag was making the rounds on social media.

To celebrate the US Supreme Court's ruling, the White House was on Friday lit up in rainbow colours.

Some activists said that Russia, too, would one day uphold gay people's right to marry but they would unlikely live long enough to see that day.
"Mostly likely I will not live to see the day when some democratic, honestly-elected president illuminates the Kremlin in rainbow colours for one day," journalist and activist Anton Krasovsky said on Facebook.

"There will be happiness. For sure. Because love wins," wrote Elena Kostyuchenko, the openly gay correspondent for Russia's top opposition newspaper Novaya Gazeta.

In 2013, Russia passed a hugely controversial law banning the promotion or display of homosexuality in front of minors.

Russia has also adopted legislation banning adoptions by gay parents.

Homophobia remains widespread in the country, and almost no public figures have come out as gay.