Alexei Navalny, Russia's most prominent opposition figure and a vocal critic of President Vladimir Putin, has been released from jail after a 20-day sentence for calling an unauthorised demonstration.

Navalny was arrested on 29 September as he planned to travel to the city of Nizhny Novgorod for a rally that had been given official permission.

But a court sentenced him for calling another rally, an unauthorised protest in St. Petersburg, President Putin's hometown.

Navalny, who plans to run for president against Putin in the country's March 2018 election, has repeatedly served jail terms connected to rallies.

After his release Sunday (22 October), Navalny said on social media that he hopes to attend an evening demonstration in the southern city of Astrakhan.

The anti-corruption campaigner this year twice called for demonstrations nationwide whose size and extent rattled the Kremlin.