Hundreds of people have been arrested amid mass protests across Russia over the arrest of opposition leader Alexei Navalny

The 44-year-old, a thorn in the side of the Kremlin for years, was arrested on January 17 when he returned to Moscow from Germany, where he had spent five months recovering from a nerve-agent poisoning.

Authorities say his stay in Germany violated terms of a suspended sentence in a 2014 criminal conviction, while Navalny says the conviction was for made-up charges.