The protest comes amid a wave of similar demonstrations across Europe, it said.
Farmers in France, Belgium, Portugal, Greece and Germany have been protesting against EU measures to tackle climate change as well as rising costs and unfair competition from abroad, the Reuters news agency reported.
Polish farmers have voiced disgruntlement with the impact of cheap food imports from Ukraine.
"Our patience has run out," the Solidarity trade union said in a statement. "Brussels' position ... is unacceptable for our entire agricultural community," it added.
"Additionally, the passivity of the Polish authorities ... regarding the import of agricultural produce and food products from Ukraine leave us with no other choice but to declare a general strike," the statement said.
(gs)
Source: rmf24.pl, Reuters