Mesic and leaders of another 43 countries will pay their respects in Auschwitz to the victims of the biggest Nazi death camp in which some 1.5 million people, mostly Jews, were killed.
"By paying respect to the victims of Auschwitz, but also the victims of all other execution sites, we will show that we know what had happened and that we will never forget it or allow it to ever happen again," Mesic told in the interview for Voice of America, published on Wednesday.
Some 7,000 Croatian Jews, who were deported from Croatia to Poland following an agreement between Germans and their Croatian allies -- the Ustasha -- were killed in Auschwitz, Voice of America said.
"We cannot and must not forget out past. We can go forwards only if we face the truth without trying to change the past or interpret it differently," Mesic said.
Speaking about the victims of the Ustasha concentration camp Jasenovac, Mesic said that innocent people were killed by those who used the idea of the Croatian state as a cover for murders, robberies and persecutions.
Croatia's chief executive said that apart from the adoption a law on banning the glorification of totalitarian regimes, announced by the Croatian government, it was important to systematically educate the youth about this issue.
"We must have books from which children will learn the real truth about World War II," Mesic said.