Protesters said they would block trucks from reaching the checkpoint between 9 a.m. and 8 p.m. every day until Sunday, public broadcaster Polish Radio's IAR news agency reported.
The farmers want the government to subsidise the prices of wheat, extend state-backed loans due to the influx of grain from Ukraine, and keep the farm tax rates unchanged, according to news outlets.
Protesters said that if their demands were not met, as of next week the blockade would be kept round the clock.
They were visited in Medyka on Thursday by MPs with the far-right Confederation group, including deputy lower-house Speaker Krzysztof Bosak, the IAR news agency reported.
The farmers received support from Polish freight carriers, who on November 6 launched a blockade of the Hrebenne, Dorohusk and Korczowa checkpoints, demanding that the European Union reinstate permits for Ukrainian transport companies entering the bloc.
Polish freight carriers also want Ukraine to reinstate certain aspects of an electronic queuing system, according to Polish state news agency PAP.
On Wednesday, Polish truck drivers launched their own blockade of the Medyka checkpoint, Ukraine's state news agency Ukrinform reported.
On Thursday, Polish transport companies announced that the protest at the Dorohusk checkpoint would be extended until February 1, according to Ukrinform.
Meanwhile, two Ukrainian truck drivers have died while waiting at the blocked checkpoints to enter Ukraine, the IAR news agency reported on Thursday, citing Ukraine's state broadcaster Suspilne.
(pm/gs)
Source: IAR, PAP, Ukrinform