Polish farmers blocked roads and staged protests at border checkpoints with Ukraine. The demonstration is part of a new wave of protests against the import of agricultural products from the neighboring country.
Warsaw has been among Kiev's staunchest supporters during Russia's nearly two-year invasion, but economic friction has strained ties between the allies, AFP reported.
Farmers in Poland claim that the opening of the EU market to Ukrainian agricultural products has led to lower prices and unfair competition.
Farmers began protests at border posts and blocked highways, snarling traffic with convoys of slow-moving tractors headed for major cities.
"We have no other choice," Marcin Vilgos, organizer of the protest in Dorohusk on the border with Ukraine, told AFP.
"The oversaturation of products from Ukraine, produced not in accordance with EU standards and procedures, is a huge burden for us," Vilgos said.
The action was organized in at least 250 towns by the main Polish agricultural trade union, which said it would last until March 10.
Asked about the protests, Polish Agriculture Minister Czeslaw Szekerski said farmers had "legitimate expectations and demands" to curb excessive imports from Ukraine.
Poland banned imports of Ukrainian grain under the previous nationalist Law and Justice government and kept it in place even though a new liberal coalition came to power in October elections.
Shekerski said Poland was in bilateral talks with Ukraine to resolve the issue, but did not rule out new bans on other product groups.
"This may be necessary for sugar if the inflow is too great. It may also be necessary for poultry meat," the minister said, adding that the government intends to raise the issue in talks with Kiev./BGNES