Campaigning officially started yesterday for Russia's presidential election in March, in which President Vladimir Putin is widely expected to win a fourth term that would keep him in power until 2024.

Russian government newspaper Rossiyskaya Gazeta published a resolution adopted by the upper house of parliament, the Federation Council, scheduling the election for March 18.

Lawmakers had voted earlier to change the date of the March vote so that it will mark the fourth anniversary of the signing of a treaty formally annexing Ukraine's Crimea peninsula.

The treaty came two days after a controversial referendum deemed illegal by the West.

Putin, who was first elected to the presidency in 2000, is widely expected to sail to victory, cementing his status as Russia's longest-serving ruler since dictator Joseph Stalin.

Putin's top critic Alexei Navalny, 41, has been barred from putting his name on the ballot because of a criminal conviction, which he says is politically motivated.

The head of Russia's Central Election Commission, Ella Pamfilova, said she was ready to hold the vote "at the right level".

Navalny, who has been campaigning in far-flung Russian regions over the past year, has called on his supporters to take part in a protest on Sunday "for free elections".

He has threatened to call for a boycott of the elections if he is not allowed to take part.