Several supporters of Russian opposition leader Alexei Navalny have been detained across the country ahead of a rally to protest Vladimir Putin's swearing-in for a fourth Kremlin term, monitors said on Friday.
Navalny, who was barred from challenging Putin in the March presidential election, has called on supporters to gather in central Moscow and other cities on Saturday, two days ahead of Putin's inauguration.
Ahead of the rallies, several members of his team across Russia have been detained, said OVD-Info, an independent monitoring group.
Activists were detained in Saint Petersburg, the Siberian city of Krasnoyarsk, the southern city of Krasnodar and in Tambov some 460 kilometres (290 miles) south of Moscow.
In Ryazan in western Russia an activist was illegally held by police for five hours over the distribution of leaflets ahead of the rally, the monitoring group said.
"Craven old man Putin thinks he is a tsar," Navalny said on Twitter. "But he is not our tsar so take to the streets on May 5."
In Moscow, Saint Petersburg and a number of other cities authorities have not granted permission for the staging of the opposition rallies.
Observers have expressed fears that the demonstrations could lead to clashes with police and mass arrests after similar protests in 2012 led to a huge crackdown on the protest movement.
In May 2012, tens of thousands took to the streets to protest Putin's inauguration for a third Kremlin term.
The rallies descended into clashes with police and more than 400 protesters were detained.
Criminal charges were brought against around 30 demonstrators and many of them were sentenced to prison terms of between 2.5 years and 4.5 years.
Putin, who has ruled Russia for almost two decades, was re-elected for a fourth Kremlin term in March.
He recorded his best ever election performance with more than 76 percent of the vote.
Opposition and independent monitors reported ballot stuffing and other cases of alleged fraud as the Kremlin pushed for a high turnout to give greater legitimacy to Putin's new term.