Poland’s Prime Minister has said that Russian President Vladimir Putin has been lying in remarks blaming Poland for the outbreak of World War II, and argued that Putin is doing it to deflect from recent Russian political failures.

Putin has said on several recent occasions that Poland bears responsibility for the outbreak of the war, deepening tensions between the two Slavic nations. On Friday the Russian ambassador to Poland was summoned to the Polish Foreign Ministry in protest.

“President Putin has lied about Poland on numerous occasions, and he has always done it deliberately,” Prime Minister Mateusz Morawiecki said in a statement on Sunday. “It usually happens in a situation when the authorities in Moscow feel international pressure caused by its actions. And this pressure is not on the historical stage but on the modern geopolitical scene.” Morawiecki pointed to several recent developments that he described as failures for Russia, including Russian athletes being suspended for doping and a failed attempt by the Kremlin “to fully subordinate Belarus to Russia.”

Putin has lashed out in recent days against a resolution adopted by the European Parliament that says the Soviet Union bears responsibility for World War II alongside Germany. The Russian leader has called that “sheer nonsense.” Putin argues that collusion with Adolf Hitler by Western powers paved the way for World War II. He has heaped scorn on Poland, citing archival documents which he asserted show the Polish ambassador to Berlin praising Hitler’s plans to rid Europe of Jews.

In one outburst, Putin denounced the ambassador as “scum” and “anti-Semitic swine.” Some opponents of Poland’s conservative government have accused the authorities in Warsaw of being too slow and passive in their response to Russia.