Russian president Vladimir Putin, running for a new six-year term in an election that his opponents say is a parody of democracy, said on Tuesday that past US elections had been rigged by postal voting.

“In the United States, previous elections were falsified through postal voting … they bought ballots for $10, filled them out, and threw them into mailboxes without any supervision from observers, and that’s it,” Putin said, without providing evidence.

Putin’s opponents say the March election in Russia is no real contest as the president wields unchallenged power and his main rival, Alexei Navalny, is serving more than 30 years in jail on charges that Mr Navalny says were trumped up.

They say the use of electronic voting creates scope for authorities to manipulate the vote in Putin’s favour without detection.