The "Down with the Green Deal" protest drew several thousands of farmers in yellow vests to downtown Warsaw, where they waved Polish flags, handed out apples and carried signs showing skulls and bones.

The European Union's Green Deal is an ambitious commitment to achieve net zero carbon emissions by 2050, making the 27-nation bloc the "first climate-neutral continent".

But it has come under fire from the fossil fuel industry and the agricultural sector, as well as from political parties on the right and far right.

"We don't agree to all the Green Deal provisions, which are harmful to Poland's economy," said Adrian Wawrzyniak, a spokesman for the Solidarity farmers' union.

"We want a referendum in Poland concerning a requirement for the president, the parliament and the government to reject the Green Deal," he told AFP.

Some protesters also condemned Ukrainian farm imports they said were undermining their revenues, as well as the policies of Poland's current pro-EU coalition government, which came to power late last year.

The right-wing opposition party Law and Justice (PiS), which has close ties with the Solidarity union, said it would also take part in the protest.

The march began at the Polish capital's historic Castle Square. Participants will walk to the European Commission's representation in Poland before continuing on to parliament.

Protest representatives are due to meet with parliament speaker Szymon Holownia to air their grievances.