Pink Floyd co-founder Roger Waters has canceled upcoming concerts in Poland over backlash prompted by his beliefs about Russia's war against Ukraine, which he attributes to "extreme nationalists" in Ukraine.

Waters was initially planning to perform two concerts at the Tauron Arena in Krakowin in April, but an arena official confirmed the events have been scrapped.

"Roger Waters’ manager decided to withdraw ... without giving any reason," Tauron Arena Krakow's Lukasz Pytko said Saturday, according to Polish media.

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The website for Waters' concert tour, "This Is Not a Drill," does not include the concerts in Krakow previously scheduled for April 21 and 22.

City council members in Krakow were expected to vote on a proposal next week to label Waters as a persona non grata. They planned to express "indignation" over his controversial views on Russia's war on Ukraine.

In an open letter to Ukrainian first lady Olena Zelenska early this month, Waters blamed "extreme nationalists" in Ukraine for setting the country "on the path to this disastrous war." 

The musician, who is British, also criticized the West, the U.S. in particular, for supplying Ukraine with weapons.

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Additionally, Waters has criticized NATO and accused the alliance of provoking Russia.

The Associated Press contributed to this report.