Poland said Wednesday it will no longer arm Ukraine and instead focus on its own defense, as the two allies clashed at a key moment in Kyiv's fightback against Russia.

In a mounting row over grain exports from Ukraine, Poland summoned the Ukrainian ambassador to protest remarks made by President Volodymyr Zelenskyy at the UN.

The Ukrainian leader said some countries were only pretending to support his nation as it wages a counteroffensive to retake land taken by Russia. Warsaw took offense at this.

Poland has been one of Ukraine's staunchest supporters after Russia launched a "special military operation" in February 2022, and is one of Kyiv's main weapons suppliers.

Much of the weaponry that the United States and other countries send to Ukraine passes through Poland, which borders Ukraine to the west.

Poland also hosts some 1 million Ukrainian refugees, who have benefited from various kinds of state aid.

Tensions between Warsaw and Kyiv were sparked by a Polish ban on Ukrainian grain imports, with the goal of protecting its own farmers.

Polish Prime Minister Mateusz Morawiecki was asked Wednesday if his country would continue to back Kyiv, despite this dispute.

"We are no longer transferring weapons to Ukraine, because we are now arming Poland with more modern weapons," Morawiecki said.

Kyiv has announced that it would lodge a complaint with the World Trade Organization (WTO) over the grain issue.

Morawiecki had warned on Wednesday that he would extend the list of Ukrainian products banned from import if Kyiv were to escalate the grain dispute.

A foreign ministry statement said that "putting pressure on Poland in multilateral forums or sending complaints to international courts are not appropriate methods to resolve differences between our countries."

Kyiv responded by calling on Poland to "leave emotion aside" after it had summoned its ambassador, urging Warsaw to adopt a "constructive" approach in the dispute.

(With input from AFP)