A government plan to increase the age for collecting state pensions brought protests across Russia's 11 time zones Sunday even though the opposition leader who called them was in jail. Nearly 300 people were reported arrested.

The plan calls for the eligibility age for retirement pensions to be raised by five years, to 65 for men and 60 for women. Opposition to it spans the political spectrum.

The rallies got started in the Far East and Siberia when it still was early morning in Moscow, where a downtown demonstration in the afternoon ended in scuffles when riot police stopped participants from marching to the Kremlin.

Alexei Navalny, the anti-corruption activist who is President Vladimir Putin's most prominent foe, urged supporters to protest the pension proposal Sunday before he was sentenced to 30 days in jail for organising an unsanctioned January protest involving a different issue.

Factory worker Olga Sokolova, 52, said she was "dumbfounded" when the proposal was introduced in June because she had hoped to retire from her physically taxing job at age 55.

"I can't keep being afraid anymore," she said of her decision to risk detention by showing up at Moscow's Pushkin Square for the protest that attracted several thousand people.

The demonstrators, predominantly people in their 20s and decades away from retirement, chanted "Russia without Putin" and held signs with messages such as "Putin, when will you go on pension?"

They later marched toward Red Square and the Kremlin, chanting "Down with the czar!" as they passed the building of the Federation Council, the upper house of parliament, and leisurely Muscovites enjoying a hot afternoon.

The group was eventually blocked by police barricades. Riot police observing from the sidelines charged the marchers with raised batons when some tried to rush through the barriers. The crowd dispersed half an hour later.