WARSAW — Classrooms remained empty across Poland on Monday as kindergarten, primary and secondary school teachers launched an indefinite national strike for higher wages, a move that challenges the right-wing government in an election year.

Up to 90 percent of teachers did not show up for work in various regions across the country, according to the ZNP Polish Teachers Union, which launched the job action demanding salary hikes of 1000 zloty (233 euros, $262) per month.

"It's hard to be satisfied with a raise of 40 to 50 euros when you know that Polish teachers earn the least in Europe," Slawomir Broniarz, ZNP president said.

"Without a compromise, the upcoming exams -- those that are set to begin on Wednesday (April 10th, 2019) -- are under serious threat," Broniarz said, adding that "only the government can provide a solution."

The strike comes as Poland's right-wing populist Law and Justice (PiS) government has rolled out a raft of generous social spending measures ahead of European elections in May and a general election this fall to shore up popularity dented by a string of scandals.

Focusing its campaign on bread-and-butter issues, the PiS has passed a pension hike and vowed to expand a child allowance it launched after taking office in late 2015.

It has also promised no income tax for employees under 26 years of age, lower income tax for pensioners and special allowances for the owners of cows and pigs.

Teachers have long complained of low wages in Poland, where public sector salaries have struggled to catch up with private sector earnings after the country shed communism in 1991.

"When you start out as a teacher right after college, you earn between 400 and 500 euros per month. A teacher with 20 years of experience earns around 600 euros per month," primary school teacher Joanna Polcyn-Ostrowska said.

That is lower than official statistics which show that Polish teachers earn between 3,000 to 5,000 zloty (700 to 1,100 euros) per month.

Last chance negotiations broke off late on Sunday after the largest unions, including the ZNP, rejected the government's offer.

"I get the impression that those who didn't sign the agreement (with the government) want chaos and confusion and that they aren't willing to reach a compromise," Beata Szydlo, Poland's deputy prime minister for social affairs told reporters on Monday. — AFP