St Petersburg: Russian President Vladimir Putin accused Britain's Prince Charles on Saturday of unacceptable and unroyal behaviour by comparing him with Adolf Hitler over Russia's stance in Ukraine.



Putin said he had not heard the comment, made by the prince to a Jewish woman who fled Poland during World War II, but asked reporters to pass on a message to the heir-to-the-British throne and the country's Prime Minister David Cameron.



"This is not royal behaviour," Putin told journalists from Reuters and other international news agencies at the Konstantinovsky Palace, built in the 18th and 19th centuries on the coast of the Gulf of Finland outside St Petersburg, Russia's former imperial capital.



"If you are angry, this means you are wrong. I have not heard this remark. If (it was said), then it is unacceptable. I think he himself realises that. He is a well-brought-up person.



"I know him and other members of the royal family personally. But I have got used to all kinds of things over the years."



According to a British newspaper, the 65-year-old prince made the comment earlier this week during a tour of Canada.



Charles told the woman, who lost relatives during the Holocaust and was recounting how she had fled Poland, that "Putin is doing just about the same as Hitler".



Putin's response came after Russia's foreign ministry had criticised Charles for his remarks, saying they did not reflect well on a future British monarch and were an "unacceptable" attempt to spread propaganda against Russia over Ukraine.



The Soviet Union lost more than 20 million people in the war and the victory over Nazi Germany is celebrated across Russia as a national triumph.



Putin, a former KGB spy, has repeatedly spoken about the sacrifices of what Russians call the Great Patriotic War and he himself lost a brother in the Nazi siege of Leningrad.



The palace where Saturday's interview took place, where G20 leaders met last September, was itself seriously damaged between 1941 and 1944 by the German armed forces.



However, Russia's annexation of Crimea has led to some in Ukraine and a few Western politicians to liken the incursion by Putin to the actions of Hitler.



Former US secretary of state Hillary Clinton had to clarify remarks in March suggesting Putin's justification for his actions over Crimea to protect ethnic Russians was reminiscent of claims made by Hitler over foreign territories.



The prince's office and Cameron, who has scolded the Kremlin for annexing Crimea and supporting pro-Russian rebels in eastern Ukraine, have declined to comment on Charles's reported remarks because they had been made during a private conversation.



However, the comments have raised some eyebrows in Britain as the royal family is not expected to voice political views publicly and the head of state is merely a constitutional figurehead.



Queen Elizabeth, Charles's 88-year-old mother, has never aired such emotive sentiments during her long reign.



"In constitutional monarchy policy and diplomacy should be conducted by parliament and government," opposition Labour lawmaker Mike Gapes wrote on Twitter. "Monarchy should be seen and not heard."