The Russian ambassador sparked outage on Friday for putting some of the blame for the start of World War II on Poland, creating a new spat and deepening the rift between the Slavic nations.

Russian Ambassador Sergey Andreev described the Soviet invasion of Poland in 1939 as an act of self-defense, not aggression. The comment prompted Poland’s Foreign Ministry to declare Saturday that the ambassador “undermines historical truth” and seems to be trying to justify Stalinist crimes.

World War II began after Nazi Germany and the Soviet Union agreed to a pact in 1939 that included a secret provision to carve up Poland and other parts of Eastern Europe. Germany soon invaded Poland from the West, which was followed by a Soviet invasion from the east more than two weeks later. Millions of Poles were killed in the war.

"Polish policy led to the disaster in September 1939, because during the 1930s Poland repeatedly blocked the formation of a coalition against Hitler's Germany,” Andreev said in an interview with the private TVN station. “Poland was therefore partly responsible for the disaster which then took place."

Poland’s Foreign Ministry expressed “surprise and alarm” at those comments, and Foreign Minister Grzegorz Schetyna summoned Andreev for a meeting on the matter Monday.

"The narrative presented by the highest official representative of the Russian state in Poland undermines the historical truth and reflects the most hypocritical interpretation of the events known from the Stalinist and communist years," the ministry said in a statement.

Prime Minister Ewa Kopacz also expressed displeasure with the ambassador.

"The role of an ambassador accredited in a country should be to build to build harmony and friendly relations between countries," Kopacz said.

Relations between Poland and Russia have never come easy. Poland has repeatedly rejected Moscow’s control Moscow’s control and embraced the West, joining NATO and the European Union. But tensions have been especially high since Russia annexed Crimea in 2014, a step that Warsaw has strongly condemned.

In other points of contention in recent days, Poland blocked a Crimean official hoping to attend an OSCE conference in Warsaw from entering the country, angering Moscow. Moscow has also protested a Polish town's dismantling of a monument to a Soviet World War II general, threating Warsaw with "most serious consequences" for that.

The Associated Press contributed to this report.