THE Prince of Wales has sparked controversy by reportedly comparing Russian president Vladimir Putin to Nazi dictator Adolf Hitler.

Prince Charles reportedly told Jewish museum volunteer Marienne Ferguson in Halifax, Nova Scotia, that the Russian leader's actions in Ukraine were similar to the Nazis who caused her family to flee the Baltic city of Gdansk for Canada in 1939.

Labour MP Mike Gapes said the prince should resign if he wanted to make such comments, but Deputy Prime Minister Nick Clegg insisted the heir to the throne should be "free to express himself".