Footage which appears to show Ukrainian nationalists beating up a young pro-Russian man before throwing him into a river has been posted online.

The attack is believed to have taken place in Donetsk, in the largely Russian-speaking eastern Ukraine where anti-government separatists have been staging angry protests.

There have apparently been growing reports of masked thugs from the pro-government side trawling the streets, claiming to be acting as agents of the Ukrainian nationalist political party.