UPDATE 3-Russians show Valentine's Day support for Navalny with candle-lit vigils

* Kremlin critic Naval treatment sparked protests

* Allies have urged supporters to gather outside homes

* Russia could face new Western sanctions(Updates after vigils end, adds quote, details)

By Gabrielle Tétrault-Farber and Vladimir Soldatkin

MOSCOW, Feb 14 (Reuters) - Supporters of Kremlin criticAlexei Navalny held candle-lit gatherings in residentialcourtyards across Russia on Sunday despite warnings that theycould be arrested.

Navalny's allies have declared a moratorium on streetrallies until the spring after police detained thousands ofpeople in the past few weeks at protests against the oppositionpolitician's arrest and imprisonment.

But they wanted Russians to show solidarity with Navalny bygathering outside their homes for 15 minutes on Valentine's Dayevening, shining their mobile phone torches and arrangingcandles in the shape of a heart.

People on social media posted pictures of themselvesholding candles or phones with flickering flashlights acrossRussia, including in the Eastern Siberia city of Irkutsk,Yekaterinburg in the Urals mountains and Novosibirsk in WesternSiberia.

However, the vigils were mostly small and sporadic, unlikethe huge street protests in recent weeks.

Navalny was arrested last month on his return from Germanyfollowing treatment for poisoning with what many Westerncountries say was a nerve agent. He was jailed on Feb. 2 forviolating parole on what he said were trumped-up charges.

He blames President Vladimir Putin for the poisoning, andWestern countries are considering new sanctions against Russia.The Kremlin denies any involvement and questions whether Navalnywas poisoned.

"Putin is fear. Navalny is love. That's why we will win,"Leonid Volkov, one of Navalny's close allies, wrote on Twitterin a call for people to gather on Sunday.

Volkov, who is based in Lithuania, is one of several Navalnyallies now abroad or under house arrest in Russia.

He urged people to flood social media with pictures ofSunday's gatherings - a new venture for the opposition thatresembles political actions in neighbouring Belarus - using thehashtag #loveisstrongerthanfear in Russian.

HUMAN CHAIN

Another activist called on women to form a human chain inMoscow on Sunday afternoon in support of Navalny's wife Yulia,who was reported to have flown to Germany this week, and otherwomen affected by the police crackdown against protesters.

More than 100 women turned up at the Arbat in central Moscowto form the chain, braving bitter cold and holding a whiteribbon measuring more than a 100 metres long.

"I really hope it will change things for the better, Isincerely want it," a woman in the chain in Moscow said.

Another smaller chain was formed in St Petersburg.

There were no large-scale arrests or clashes with thepolice.

The OVD-Info protest monitoring group said nine people weredetained in the city of Kazan, some 820 km (510 miles) east ofMoscow, following a rally against repression. Six of them hadbeen released already.

Russian law enforcement agencies on Thursday said thatpeople taking part in unsanctioned rallies could face criminalcharges.

Rights groups have accused police of using disproportionateforce against protesters in recent weeks. The Kremlin has deniedrepression by police and says the protests were illegal becausethey were not approved and risked spreading COVID-19.

Putin has blamed the pandemic for fuelling the protests andtried to downplay the role of Navalny. Speaking at a meeting ofchief editors of mostly pro-government media last week, Putinrefused to call Navalny by name, referring to him as "thedefendant".

"This defendant is being used just as people's fatigue isemerging all over the world, including in our country," he said."Irritation has piled up, people have become disgruntledincluding by their living conditions, by the level of income."

Navalny was in effect an outlet for anger at the authoritiesover the pandemic, he said.(Reporting by Gabrielle Tétrault-FarberAdditional reporting by Vladimir Soldatkin and Lev SergeevEditing by Katya Golubkova, David Goodman and Frances Kerry)