Ukrainian President Volodymyr Zelensky has condemned the weeks-long blockade of the border by Polish truck drivers and farmers, which his government says threatens the country's security.
Polish farmers are blocking Ukrainian cargo in protest against what they say is unfair competition.
The scandal has strained relations between the neighbors, although Poland has been one of Ukraine's staunchest supporters since Russia invaded in February 2022.
"The things that are happening on our western border, on the border with Poland, cannot be considered normal or ordinary," Zelenskiy said, adding that the situation "demonstrates the erosion of solidarity on a daily basis."
Road traffic to EU member Poland has been a lifeline for Ukrainian companies' exports since the Russian invasion shut down major trade routes across the Black Sea.
But the increase in shipments has angered Polish logistics companies and farmers, who say their Ukrainian competitors are undercutting them.
"In reality, the situation is not related to grain, but rather to politics," Zelenskiy said, arguing that only 5 percent of agricultural exports cross the Polish border.
Six border points are blocked by the Polish side, said the Minister of Infrastructure Oleksandr Kubrakov.
"Blocking the border is a direct threat to the security of the defending state," Kubrakov said on Facebook.
"They are blocking everything. There are fuel trucks. There were cases a few days ago when protesters did not let several trucks with weapons pass," Kubrakov told state television.
A Polish official said there was a queue of about 600 trucks at the Dorohusk border crossing waiting to leave Poland and head for Ukraine.
"The expected waiting time for this number of trucks to leave the country is approximately 232 hours," Michal Derus, spokesman for the Chamber of Tax Administration in the Polish city of Lublin, told AFP.
He said more than two dozen trucks crossed the border with Ukraine overnight, but "not a single truck entered Poland."
"It should therefore be assumed that it is a total blockade," he said.
The situation is expected to escalate on Tuesday, when Polish farmers call for a halt to all border traffic with Ukraine. /BGNES