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.

Thousands of protesters in Serbia have rallied against President Aleksandar Vucic, demanding early parliamentary elections.

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.