Britain's heir to the throne reportedly compared Russian President Vladimir Putin to Nazi dictator Adolf Hitler over Russian actions in Ukraine.
Prince Charles' alleged remark about Putin was made during a four-day tour of Canada when he spoke to a woman who fled the Nazis and lost family members in the Holocaust.
Russia's Foreign Ministry said the prince's remarks were "unacceptable, outrageous and low", and Russia's ambassador to London demanded face-to-face talks with officials at the British Foreign Office.
A spokesman for the eldest son of Queen Elizabeth II said earlier: "We do not comment on private conversations. But we would like to stress that the Prince of Wales would not seek to make a public political statement during a private conversation."
Charles was being shown around the Museum of Immigration in Halifax, Nova Scotia, along with his wife Camilla. The royal couple paid tribute to World War II veterans and their families, and during the course of the visit they spoke to museum volunteer Marianne Ferguson who told Prince Charles how she had fled to Canada with her family in 1939, not long before Hitler annexed the Baltic coastal Free City of Gdansk.
After the meeting Charles, Ferguson told the 'Daily Mail' that Prince Charles had remarked "And now Putin is doing just about the same as Hitler." The newspaper reported that the prince had made his comments while surrounded by media and that they had been heard by several witnesses.
