In an action called "Noon against Putin," Russians who oppose the veteran Kremlin leader went to their local polling station at midday to either spoil their ballot paper in protest or to vote for one of the three candidates standing against Putin, who is widely expected to win by a landslide.
Others had vowed to scrawl the name of late opposition leader Alexei Navalny, who died last month in an Arctic prison, on their ballot paper.
Navalny's allies broadcast videos on YouTube of lines of people queuing up at different polling stations across Russia at midday who they said were there to peacefully protest.
Navalny had endorsed the "Noon against Putin" plan in a message on social media facilitated by his lawyers before he died.
"There is very little hope but if you can do something (like this) you should do it. There is nothing left of democracy," one young woman, who did not give her name and whose face was blurred out by Navalny's team, said at one polling station.
Another young woman at a different polling station, whose identity had been disguised in the same way, said she had voted for the "least dubious" of the three candidates running against Putin.
Voters across Russia's 11 time zones have taken part in presidential elections. (AP PHOTO)
Despite the protesters - who represent a small fraction of Russia's 114 million voters - Putin is poised to tighten his grip on power in the election that is expected to deliver him a big victory.
The 71-year-old Putin faces three token rivals - veteran Communist Nikolai Kharitonov, ultranationalist Leonid Slutsky and Vladislav Davankov, deputy chairman of the lower house of parliament and candidate for the New People party - who have refrained from any criticism of him.
Police arrested dozens of people who joined the midday protests, with the OVD-Info human rights media project counting about 50 arrests up to early afternoon, half of them in Kazan, a city on the Volga River 700km east of Moscow.
Opposition politician Boris Nadezhdin, who was removed from the ballot in his effort to challenge Putin, took part in the midday protest in Moscow.
Nadezhdin was received with cheers from students at a polling place on the campus of the Moscow Institute of Physics and Technology, as a video he posted on Telegram showed.
"I think you will still have the chance to vote for me," he told those gathered.
He announced plans to publish his own post-election surveys after the polling stations had closed.
In the video, Nadezhdin is surrounded by dozens of students chanting his name and later the name of the university.
The politician, who teaches at the university, thanked them for their support and promised to continue fighting.
His goal, he said, was for his Citizens' Initiative party to win the upcoming parliamentary elections.
Nadezhdin caused a stir in January when thousands of Russians queued up to sign his petition to get on the ballot.
Nadezhdin, 60, said he was able to collect twice the required 100,000 signatures but the Kremlin-controlled election commission excluded him.
They said there were too many incorrect signatures.
The Kremlin casts political allies of Navalny - most of whom are based outside Russia - as dangerous extremists out to destabilise the country on behalf of foreign forces.
It says Putin enjoys overwhelming support among ordinary Russians, pointing to opinion polls which put his approval rating above 80 per cent.
With Russia's vast landmass stretching across 11 time zones, protest voters were scattered rather than concentrated into a single mass, making it hard to estimate how many people turned up for the protest event.
Reuters journalists saw a slight increase in the flow of voters, especially younger people, at noon at some polling stations in Moscow and Yekaterinburg, with queues of several hundred people.
Some said they were protesting though there were few outward signs to distinguish them from ordinary voters.
Leonid Volkov, an exiled Navalny aide who was attacked with a hammer last week in Vilnius, estimated hundreds of thousands of people had come out to polling stations in Moscow, St Petersburg, Yekaterinburg and other cities.
Reuters could not independently verify that estimate.
At polling stations at Russian diplomatic missions from Australia and Japan to Armenia, Kazakhstan and Georgia, hundreds of Russians stood in line at noon.
with DPA
