(Updates with detentions reported in Moscow)
SOCHI, Russia, Feb 7 (Reuters) - Russian police detained gay rights activists who tried to protest on Moscow's Red Square and in St Petersburg on Friday, shortly before Vladimir Putin opened the Sochi Winter Olympics, gay rights activists said.
The protests followed international criticism of a law the Russian president signed last year banning the spread of "gay propaganda" among minors.
Police in Moscow and St Petersburg did not immediately comment on the reports by the gay activists, who said 10 protesters were detained in Moscow and four in Russia's second city.
A list posted by one rights activist on Facebook said two of those detained in Moscow were women from Sweden.
In St Petersburg, the protesters were detained after unfurling a banner declaring "Discrimination is incompatible with the Olympic Movement", gay rights group All Out said.
Putin, who has staked his political and personal reputation on staging a successful Games, has said there will be no discrimination at the Games and the Russian government says the law is needed to protect young people.
Gay rights groups say the new law discriminates against gays and that it has fuelled attacks on homosexuals in Russia, but Putin says it is needed to protect young people. (Reporting by Thomas Grove, Editing by Timothy Heritage)