Protesters have pelted snowballs at riot police in clashes in Russia after a rights activist was sentenced to four years in a penal colony.

Dozens of people were detained and injured with one protester suffering a “smashed head”, says monitoring group OVD-Info.

Crowds gathered outside a courtroom in Bashkortostan to support local activist Fail Alsynov, with officers firing tear gas at the crowd.

Some reports say there are a few thousand people at the protest, which has been going on for several days in freezing temperatures of around -20C.

Alsynov was jailed for inciting ethnic hatred, which he denies.