Thirty percent of Poles are unaware that 22,000 Polish officers were killed by Stalin’s NKVD in 1940.

In the poll for the Mareco Polska centre, 21 percent of respondents said they didn’t know who killed the officers in the massacre which commemorates its 70th anniversary in April, while nine percent said that it was “the Nazis”, the official line for years following the war in communist Poland.

Historical ignorance is most marked among Poland’s young people, with 48 percent under 20 years old not knowing who was responsible in Katyn.