MOSCOW - Kremlin critics called for massive protests at Russian polling stations on Sunday for the final day of a presidential election that is guaranteed to cement Vladimir Putin's hardline rule.
The three-day vote has already been marred by a surge in fatal Ukrainian bombardments and a series of incursions into Russian territory by pro-Ukrainian sabotage groups.
There have also been acts of protest in the first days of polling, with a spate of arrests of Russians accused of pouring dye into ballot boxes or arson attacks.
Before his death in an Arctic prison last month, opposition leader Alexei Navalny, who galvanised mass anti-Putin rallies, urged Russians to protest on Sunday.
His widow, Yulia Navalnaya, has reiterated his call in the run-up to the election and said protesters should show up in large numbers at the same time to overwhelm polling stations.
She called for protestors to spoil ballots by writing "Navalny" on them, or vote for candidates other than Putin.
Any public dissent in Russia has been harshly punished since the start of Moscow's offensive in Ukraine on 24 February 2022 and there have been repeated warnings from the authorities against election protests.
The 71-year-old Putin, a former KGB agent, has been in power since the last day of 1999 and is set to extend his grip over the country until at least 2030.
If he completes another Kremlin term, he would have stayed in power longer than any Russian leader since Catherine the Great in the 18th century.
He is running without any real opponents, having barred two candidates who opposed the conflict in Ukraine.
The Kremlin has cast the election as an opportunity for Russians to show they are behind the assault on Ukraine, where voting is also being staged in Russian-held areas.
The voting will wrap up in Kaliningrad, Russia's westernmost time zone, at 6pm GMT and an exit poll is expected to be announced shortly after that.
A concert on Red Square is being staged on Monday to mark 10 years since Russia's annexation of Ukraine's Crimea peninsula -- an event that is also expected to serve as a victory celebration for Putin.