He used the Russia Day holiday to promote a controversial reform of the constitution which could keep him in office until 2036, the BBC reported.

Putin (67) has dominated Russia for the past 20 years whether as president or prime minister.

Moscow lifted lockdown curbs this week despite a huge number of infections.

But there was confusion as the mayor of the capital, Sergei Sobyanin, urged people to stay at home during Friday's holiday and another on June 24, which marks victory in World War II.

About 510,000 people have tested positive for coronavirus in Russia, the third-highest number of cases in the world after the US and Brazil. Russia has recorded 6,705 deaths amid accusations of under-reporting by the authorities.

His last public appearance was on May 9 when he attended a Victory Day ceremony - the traditional parade has been postponed until June 24. Since then he had been working from his country residence outside Moscow.

Flanked by allies, he attended an open-air flag-raising ceremony in western Moscow on Friday.

In his speech, he urged Russians to turn out and vote for the constitutional reform in a referendum on July 1, saying he was certain that an "absolute majority" of Russians backed it.

The reform would effectively allow him to stand for two more terms as president after his current six-year term expires in 2024.

Putin critics have accused the authorities of trying to bribe Russians to turn out for the vote.

The city of Moscow, for example, is planning to hand out shopping vouchers to those who vote, justifying the offer as an incentive to boost consumer demand after lockdown.

Georgy Alburov, an ally of opposition leader Alexei Navalny, said the mayor of Moscow had failed to support small businesses during the lockdown but could "find plenty of money if he has to lure in people to 'polling stations' to affirm Tsar Putin", media reports said.

Russia, like many countries, has been suffering acute economic hardship because of its lockdown, which began at the end of March.

Amid rising unemployment, there have been signs of growing disillusionment with the Kremlin.