Poland's president has revoked the country's highest state honor awarded to Ukrainian President Volodymyr Zelenskyy, following a dispute over Kyiv's decision to rename a military unit after the Ukrainian Insurgent Army (UPA), a nationalist force whose wartime actions remain a source of deep tension between the two countries.

President ​Karol Nawrocki's decision was ​likely to ⁠unleash a severe diplomatic crisis between the neighbours just days ahead of a conference on Ukraine's reconstruction in the Polish city of Gdansk.

"In light of President Volodymyr Zelenskiy's consent to name one of the units of the Armed Forces of Ukraine "Heroes of the UPA,"... I have decided to revoke the Order ⁠of ⁠the White Eagle from the President of Ukraine," Nawrocki said in a statement.

Some Ukrainians regard the UPA as heroes ​for the resistance they mounted against the Soviet Union and Nazi Germany, and ⁠as symbols ‌of ‌Kyiv's struggle for independence from ⁠Moscow.

But the UPA was ‌also involved in the Volhynia massacres, a series of ​killings from 1943 to ⁠1945 in which Poland ⁠says around 100,000 Poles were killed by Ukrainian ⁠nationalists. Thousands of ​Ukrainians also died in reprisal killings.

In response to the decision, Ukrainian Foreign ​Minister Andrii Sybiha said ⁠⁠that Poland ​committed ​a "strategic error" ⁠with the decision by its president to strip Ukrainian leader Volodymyr Zelenskyy ⁠of a ⁠state award.

"The decision to strip the president of Ukraine ⁠of the Order of the White ​Eagle is a ​strategic ⁠error ‌by ‌the President ⁠of Poland ‌that ​only benefits ⁠Moscow," ⁠Sybiha wrote ⁠on ​Facebook.