A Russian court on Monday sentenced top opposition politician Alexei Navalny, who wants to unseat President Vladimir Putin in next year's election, to 20 days in jail over repeatedly violating a law on organising public meetings.

The 41-year-old charismatic anti-corruption campaigner was detained on Friday as he was planning to travel to a rally in a provincial city. Police said he was held over "multiple calls to participate in an unauthorised public event."