Former world chess champion Gary Kasparov has described Russian President Vladimir Putin as a cancer during an address to a US Senate inquiry on Ukraine.

Together with the former leader of Georgia Mikhail Saakashvili the two men warned the foreign relations committee that Putin has plans to expand and must be stopped.

Kasparov who lives in self-imposed exile in the US also offered a gloomy outlook for Russia’s political opposition following the murder of Boris Nemtsov.