Russian opposition leader Alexei Navalny attends a hearing after he was detained by police as he left his Moscow home on Friday to take part in a pre-election rally in Nizhny Novgorod, at a court in Moscow, Russia October 2, 2017. REUTERS/Sergei Karpukhin

MOSCOW (Reuters) - Kremlin critic Alexei Navalny called on his supporters on Wednesday to hold street protests this weekend across Russia, in defiance of an official ban, to demand that Navalny be allowed to run in next year’s presidential election.

Navalny, a vocal critic of President Vladimir Putin, was jailed for 20 days on Monday for repeatedly violating laws governing the organization of public meetings and rallies.

His arrest, the third this year, means that he will miss a campaign rally planned in Putin’s hometown of St Petersburg on Oct. 7 - the Russian leader’s birthday.

Appealing to his supporters via his Facebook page, Navalny called on them to attend protests in both St Petersburg and Moscow on Saturday, adding that 80 of his support groups were meanwhile organizing protests across Russia.

“Our task is to make Oct. 7 the day when every decent person will pronounce aloud or to himself at least these two demands: political competition and Navalny’s admission to the polls,” he said in the appeal, which he said he had dictated from jail.

The authorities have banned the planned weekend rallies in Moscow and St Petersburg, and the Kremlin warned on Tuesday that those calling for the protests would be prosecuted.

Putin said earlier on Wednesday that he had not yet decided whether he would run for re-election in March 2018, something he is widely expected to do.

Opinion polls show that if both Putin and Navalny were running, the incumbent would win by a wide margin.