2003 file photo of Russian President Vladimir Putin, left, as he shares a limousine with Britain's Prince Charles in London, during a visit to Britain by Putin. Photo / AP
But Deputy Prime Minister Nick Clegg insisted the prince was "free to express himself" and told the BBC: "I have never been of this view that if you are a member of the royal family somehow you have to enter into some Trappist vow of silence."
Officials in Moscow refused to comment on the claims, which come shortly before Prince Charles is due to meet with President Putin next month to mark the 70th anniversary of the D-Day landings in Normandy.
Ms Ferguson told the Prince she fled to Canada with her family shortly before the Nazis annexed the Baltic coastal Free City of Gdansk in 1939.
After meeting Charles, Mrs Ferguson, 78, said: "the Prince said, 'and now Putin is doing just about the same as Hitler'.
"I must say that I agree with him and am sure a lot of people do.
"But I was very surprised that he made the comment as I know they (members of the Royal Family) aren't meant to say these things.
"I told the Prince that while my family and I were lucky to get a permit to travel, many members of my relatives had permits but were unable to get out before the war broke out on September 1.
"They were sent to the concentration camps and died."
A spokesperson for Clarence House said it would not comment on private conversations but stressed: "the Prince of Wales would not seek to make a public political statement during a private conversation."
Ms Ferguson later told the BBC it was "just a little remark.
"I didn't think it was going to make such a big uproar," she said.
- UK Independent
