Polish farmers protesting this month against what they say is unfair competition from Ukraine and European Union environment regulations have blocked border crossings with Ukraine and motorways, and spilled Ukrainian produce from train wagons.

"These pictures show 160 tons of destroyed Ukrainian grain. The grain was in transit to the port of Gdansk and then to other countries," Deputy Prime Minister Oleksandr Kubrakov posted on X with photographs of mounds of grain spilled from train wagons.

"The fourth case of vandalism at Polish railway stations. The fourth case of impunity and irresponsibility."

Previous incidents of grain being spilled from trains took place on the border with Ukraine.

"We know that protests that take the form of spilling grain are not good," Polish Agriculture Minister Czeslaw Siekierski told a news conference. But he added that he thought that sometimes the reaction to such incidents from the Ukrainian side went too far.

Lidia Kowalska, a police spokesperson from the northern Polish city of Bydgoszcz, said the incident took place in the nearby village of Kotomierz and the product spilled was corn.

"The details and circumstances are being investigated," she told Reuters. "At 0930 we received a report about grain that had spilled out, it turned out that it was from eight wagons."

(Reporting by Dan Peleschuk and Alan Charlish; Editing by Hugh Lawson and David Evans)