Poland opposes the EU-Mercosur free trade deal with South American countries in its current form, the prime minister said on Tuesday, joining France in standing against an agreement European farmers say will expose them to unfair competition.

Brazil has been pushing to have the EU-Mercosur agreement signed by the end of the month while it holds the presidency of the G20. Advocates of the deal, including the EU's biggest economy Germany, say it will open up more markets for their exports.

Farmers say the agreement with the Mercosur bloc that includes Brazil, Argentina, Bolivia, Paraguay and Uruguay will create unfair competition for EU farmers and food makers as it will allow large imports of products that are not bound by the same strict regulation they face in the EU.

"Poland does not accept, and we are not alone, we will not accept in this form the agreement with the countries of South America, that is the Mercosur group, on free trade," Prime Minister Donald Tusk said before the start of a government meeting.

Polish farmers blocked the Medyka border crossing with Ukraine in protest against the deal on Saturday. This followed large protests in France and in Brussels.

French President Emmanuel Macron reiterated his opposition to a deal with Mercosur as proposed during a visit to Argentina this month.

France, the EU's largest agriculture producer, has been trying to convince other EU members to form a minority bloc against the deal.

The EU-Mercosur deal would allow the entry of an additional 99,000 tons of beef, 190,000 tons of sugar, 180,000 tons of poultry meat, 1 million tons of maize, producers have said.