Queues formed outside Moscow polling stations on Sunday as some voters heeded a call by supporters of late opposition leader Alexei Navalny to cast protest votes in Russia's presidential election.

AFP reporters at two polling stations saw larger numbers of voters at noon (0900 GMT) compared to earlier in the day following the call for a "Midday Against Putin" protest.

Navalny, President Vladimir Putin's most prominent rival, died in mysterious circumstances in an Arctic prison last month.

His widow Yulia Navalnaya had called on people to go to polling stations at the same time and spoil their ballots as a protest.

Since the start of Russia's full-scale offensive in Ukraine in 2022, public dissent in Russia has been stifled and government critics have been jailed or forced to flee.

After casting his ballot at a polling station where Navalny used to vote, IT worker Alexander said he came because this was one of the few ways he could protest.

"If I hadn't done this, I would have felt like a coward," the 29-year-old said.

Elena, 52, said people were "too afraid" to come out in large numbers.

"I don't want Russia, my homeland, to be like this... I love my country, I want it to be free."

Natalya, a 65-year-old pensioner, said she came with her friend Elena, a 38-year-old engineer, to spoil her ballot in memory of Navalny.

"I came to give my farewell to him. He is a hero to me," Natalya said.

Elena added: "This is our only opportunity to express our opinion."

  'Symbolic action' 

 Images shared on social media by Navalny's team showed larger queues of voters at other polling stations in Moscow and elsewhere in Russia.

At another polling station in southwest Moscow, Leonid, an 18-year-old student, said there were "not that many people" taking part in the protest but he was "just happy that some people came".

The polling station in a school was where Navalny scored his highest result -- 70 percent -- in his failed bid to become Moscow mayor in 2013.

Navalny later attempted to run against Putin in the 2018 presidential election but his candidacy was rejected.

Olga Mironenko, a 33-year-old IT worker, said she had never voted for Putin but it was difficult to express her views in a country where "you can't even express your opinion on social media".

She said it had felt good to come to the polling station and be "with people who are on the side of light and truth".

Denis, 21, who works in advertising, said: "I came to express solidarity with a very important person. It's a symbolic action."

"This election is a way to honour Navalny's memory," he said.