Russian protest leader, Alexei Navalny, was sentenced to 30 days in jail on Monday for organising unauthorised rallies.
That will prevent Navalny from rallying amid regional and parliamentary elections next week.
A fierce critic of Russia’s leadership, Navalny has previously been jailed numerous times.
Navalny was detained near his home over the weekend.
He was sentenced for repeatedly violating legislation against holding unauthorised public events.
“Let them not think that my arrest will change something,” Navalny wrote on Twitter after being sentenced, calling for his supporters to protest on the election day.
Navalny has been an adamant opponent of government plans to raise the pension age.
A referendum on that issue could make it on the ballot on Sept. 9.
“Please be more active in helping gather people for the protest against raising the pension age on Sept. 9,” Navalny said on Twitter.
The Russian parliament has given tentative approval to raising the pension age from 55 to 63 for women and 60 to 65 for men.
If it becomes law, it would be the first time in 80 years that the age would be raised.
The possibility has evoked outcry, particularly for men.
Forty-three per cent of Russian men are not expected to reach the age of 65, according to World Bank data from two years ago.