The European Union will represent Poland, Hungary and Slovakia in a trade dispute with Ukraine at the World Trade Organization (WTO) over the three EU members' ban on Ukrainian grain, European Commission spokesperson Miriam Garcia Ferrer said on Thursday.

The three countries said the bans were imposed to protect their farmers from a surging influx of grain and other food products from Ukraine, a shift driven by Russia's Black Sea blockade during which Ukraine's grain exports have to transit through the EU.

Kyiv said it had filed a legal action against the three countries at the WTO earlier this week, a move the three countries said was unfounded.

The three countries' import bans were an extension of a previous EU-wide ban, which the European Commission decided to suspend last week. Their insistence in having the bans remain in place marked a widening wedge between EU members, with some governments criticizing them for not supporting Ukraine in its conflict with Russia. 

Trade policies are under the exclusive purview of the EU, Ferrer said, adding that it is the EU that negotiates and sets up trade agreements, not its members. 

The statement suggests both the EU's mandate to argue in their favor at the WTO and the three countries' lack of authority to impose unilateral bans.

Amid heightening tension between Ukraine and the three eastern EU countries, Poland, one of Ukraine's staunchest supporters in its fight against Russia, said it will stop sending arms to Ukraine. It followed Ukrainian President Volodymyr Zelenskyy's comment that some countries were just pretending to help his country.

(Cover: A security staff member guards the entrance to the headquarters of the World Trade Organization in Geneva on June 11, 2022. /CFP)