Russian voters have overwhelmingly backed a referendum on constitutional changes that include a provision allowing Vladimir Putin - who has already served for some two decades - to remain in power until 2036.

With nearly all of the ballots counted, the tally for the voting that has taken place over a full week, showed a 78% “yes” vote, according to Russia"s Central Election Commission. The commission estimated the turnout was 65% of eligible voters.

The opposition accused the government of rigging the vote.

Russia’s constitution had required Putin to step down after his current six-year term expires in 2024.

The amendments to the constitution up for the referendum vote had been passed weeks ago by Russia"s parliament, but Putin had insisted that they be approved by voters to give the changes legitimacy.