Three former Polish presidents have accused the conservative PiS government of threatening democracy and the constitutional order. PiS is under pressure from the EU and Polish opposition for controversial reforms.
Poland's ruling Law and Justice (PiS) party on Monday drew renewed criticism it was dragging the country away from democracy.
In a front page appeal on the "Gazeta Wyborcza" daily, former presidents Lech Walesa, Aleksander Kwasniewski and Bronislaw Komorowski accused the PiS of having "no intention of abandoning this path of demolishing the constitutional order" and "paralyzing the work of the Constitutional Tribunal and all of the judicial authorities."
Since sweeping to power in the October elections, the PiS has implemented a number of controversial reforms, including an overhaul of the constitutional court and media laws that critics and EU institutions worry threaten democratic checks and balances.
"An attempt by the Law and Justice to create its own (legislative) order represents a usurpation of power," the letter's authors wrote. "Those responsible for violations of the Constitution will face the consequences."
Three former foreign ministers and four leaders of the anti-Soviet Solidarity movement also signed the letter.
Prime Minister Beata Szydlo dismissed the letter, saying those opposed to the PiS ignore the mandate for reforms the party received from the electorate.
"These people do not want to accept the free choice that the Poles have made," Szydlo said.
The ruling party, which also controls the presidency, has consistently denied attempting a power grab, even as the EU has put the government under watch for violations of bloc rules. The government in turn has accused the EU of meddling in Poland's internal affairs.
However, the political heavyweights said in their appeal that the EU's "discussions, resolutions, opinions and recommendations are not an 'interference in Poland's internal affairs' but reflect a justified concern over our state and the rights of its citizens."
"From a trusted, valued partner in the EU and NATO, we're on our way to becoming a nation of sorrow," the leaders wrote. "Let's return to a constitutional democracy."
cw/jlw (AFP, AP, dpa)