MOSCOW — Russians were voting on Sunday in an election set to hand President Vladimir Putin a fourth Kremlin term but slammed by the opposition as a sham as tensions with Britain escalated over the poisoning of a former Russian double agent.

With the vast country stretching across 11 time zones, polls opened in the Russian far east at 2000 GMT on Saturday and will close in Kaliningrad, the country’s exclave on the EU border, at 1800 GMT on Sunday.

Putin’s main challenger Alexei Navalny has been barred from taking part in the poll for legal reasons, and the result of the election is in little doubt, with overall turnout likely to provide the only element of surprise.

A total of 107 million Russians are eligible to cast their votes in Sunday’s election in the world’s biggest country, but some analysts say that after 18 years of leadership — both as president and prime minister — Putin fatigue may be spreading, with many Russians are expected to skip the polls.

The Kremlin needs a high turnout to give greater legitimacy to a new mandate for Putin, who is already Russia’s longest-serving leader since Joseph Stalin.

By 0700 GMT, turnout stood at 16.55 percent, compared with 6.53 percent at the same hour during the 2012 vote, said Central Electoral Commission head Ella Pamfilova.

Many of those who cast their ballots voted for Putin, praising him for lifting the country out of the post-Soviet quagmire.

“Of course I’m for Putin, he’s a leader,” said Olga Matyunina, a 65-year-old retired economist.

“After he brought Crimea back, he became a hero to me. Last election I didn’t vote for Putin, I don’t even remember who I voted for.”

At many polling stations the atmosphere was festive, with patriotic songs blasting out of speakers outside and cheap food available to voters.

Casting his ballot in Moscow, Putin said he would be pleased with “any” result that gave him the right to continue serving as president.

“I am sure the program I am offering is the right one,” he said.

Navalny, 41, has denounced the election as a sham and urged Russians to boycott the vote.

He has deployed more than 30,000 observers to monitor the polls and on Sunday, his team — which calls the vote “a staged procedure to re-appoint Putin” — began publishing a rolling list of violations from polling stations.

Navalny, who faces a 30-day jail sentence, had been expected to spend election day behind bars but remained free on Sunday.

“I will not go to vote. What for?” said Boris Limarev, a 39-year-old manager, as he walked his dog near a polling station in southwest Saint Petersburg.

“It’s clear to everyone who will be elected.”

“And the rest of the candidates are clowns,” interjected his wife Anna, 35.

“Another six years of slavery,” said a piece of paper made up to look like a ballot which was attached to a porch on a central Moscow street — in an apparent reference to Putin’s next term in office. — AFP