The leader of Russia's opposition Levy Front (Left Front) movement, Sergei Udaltsov, has been sentenced to 30 days in jail over protests in July against the government's proposal to raise the retirement age.

Udaltsov’s wife, Anastasia Udaltsova, tweeted the news about the conviction of her husband on August 14 after a court in Moscow found him guilty of "repetitive violations of public gathering regulations."

According to Udaltsova, her husband was sentenced for "public destruction of portraits of people resembling leaders of the nation," which the court defined as a violation of the regulations.

Tens of thousands of Russians rallied across the country on July 28 against the proposal.

Udaltsov was one of the organizers of rallies in Moscow, where thousands protested against the proposed reforms.

Legislation now under consideration by lawmakers would raise the retirement age from 60 to 65 for men by 2028 and from 55 to 63 for women by 2034.

Russian officials have warned for years that the pension age needs to be raised to take into account the country's demographics, labor force, and projected budgets.

President Vladimir Putin's public-approval ratings have slipped noticeably since the plan was announced in June, sparking outrage across Russia.

Udaltsov, a prominent Russian opposition activist, was released from prison in August 2017 after serving 4 1/2-year prison sentence he received over a May 2012 protest against Putin and the Russian government.

In that case, Udaltsov was convicted of organizing "mass disorder" after the 2012 protest broke into violence. Demonstrators and police blame each other for the violence.