World Bulletin / News Desk

Russians were voting 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.

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.