His grandfather's past came to light when his political rivals -- twin brothers Lech and Jaroslaw Kaczynski -- publicized it during the 2005 election campaign, Haaretz reported.
Tusk's family, which is from the Baltic Sea port city of Gdansk, "like the Jews, are people who were born and live in border areas and were suspected by the Nazis and by the Communists of being disloyal," Tusk told Haaretz in an interview.
He said he had no regrets about his background because "it's my family's biography. As a historian and as a man, I prefer to know the painful truth over a pleasant lie."
Tusk's grandfather was forced to serve in the Wehrmacht, Adolf Hitler's army, during World War II.
It will be Tusk's first visit to Israel, and the first visit by a Polish leader in nearly a decade. His visit will kick off Polish Year in Israel 2008-09 with a sound and light show by two Polish artists in a Tel Aviv municipal building.