Morawiecki, who serves as deputy leader of the opposition Law and Justice (PiS) party, was speaking at a press conference in front of the Home Army monument in Warsaw on Tuesday.
He said President Volodymyr Zelensky's recent conduct had been "extremely harmful and irresponsible," referring to Ukraine's decision to name a military unit after the Ukrainian Insurgent Army (UPA), which he called "a shameful act."
Earlier this month, President Karol Nawrocki responded to the move by revoking the Order of the White Eagle previously awarded to Zelensky, Poland's highest state honour.
Morawiecki called on Tusk's government to push through parliament bills drafted by PiS and separately by the Polish president, which would criminalise the promotion of symbols glorifying the UPA and Stepan Bandera's nationalist movement.
He insisted the 1943 massacre of Poles in Volhynia should not be downplayed as a regional dispute.
"This was genocide, carried out with particular cruelty," he said.
He also called for the deportation of anyone in Poland displaying symbols glorifying the UPA, arguing the proposed law would give authorities clear legal grounds to act.
In a symbolic gesture, Morawiecki announced he would hand over a Ukrainian state honour – the Order of Prince Yaroslav the Wise, awarded to him by Zelensky in 2022 for Poland's support of Ukraine – to a museum being built in Chełm to commemorate victims of the Volhynia massacre.
He said he hoped it would give visitors reason to reflect on the atrocity.
A fellow PiS politician, MEP Michał Dworczyk, said he would do the same with honours he received while serving as head of the Prime Minister's office.
Dworczyk added that PiS MEPs plan to submit an amendment to a European Parliament report on Ukraine, due to be voted on next week, seeking to have the chamber formally recognise the UPA as a Nazi-affiliated organisation responsible for mass crimes against Polish and Jewish civilians.
The historical dispute between Warsaw and Kyiv focuses on the legacy of the UPA, a nationalist force that fought for Ukrainian independence during and after World War II.
Many Ukrainians regard UPA members as national heroes for resisting both Nazi Germany and the Soviet Union and for their role in Ukraine's struggle for independence.
In Poland, however, the group is widely associated with the Volhynia massacres, a campaign of ethnic violence in 1943-1945 in which Polish authorities say about 100,000 Poles were killed by Ukrainian nationalists.
Tensions over the wartime killings have periodically strained relations between Warsaw and Kyiv, despite Poland's strong political and military support for Ukraine since Russia's full-scale invasion in 2022.
(ał)
Source: PAP