The Kremlin said on Monday that it could not rule out the possibility that anti-government protests in Serbia, a close Russian ally, could be an attempted "colour revolution", but that it was sure the Serbian leadership could restore calm.

Serbia's president announced Sunday more arrests of anti-government protesters following clashes with police at a massive rally demanding an early parliamentary election. Dozens have already been detained.

Riot police fired tear gas at thousands of anti-government protesters in Serbia’s capital on Saturday. The major rally in Belgrade against Serbia’s populist president, Aleksandar Vucic, was called to back a demand for an early parliamentary election.