Thousands of Czech schools shut their doors on Monday and staged a rare one-day strike to demand higher funding for education, which they say is threatened by the centre-right cabinet's austerity policies.

Unions said the strike was joined by most schools in the country of 10.9 million and was supported by other unions in the public and private sectors amid displeasure with the government's efforts to cut budget deficits.

Teachers unions have said the 2024 education budget plan would threaten the quality of schooling due to inadequate resources for teaching languages and other subjects in small groups, and low funding for teachers' assistants and other support professions, such as cooks.

Josef Stredula, chief of the largest union group CMKOS, said the government had ignored the impact of inflation including energy prices on living standards and its package of tax hikes and spending cuts approved by parliament was unacceptable.

"The government has been ignoring the tough life it has caused," he said on Czech Television.

Other professions will join the strike, including unions at the largest private manufacturer Skoda Auto, which planned a two-hour work stoppage. Stredula said around 1 million people would support the strike in some form.

The government has said the strike was unfounded after it reversed planned cuts and penned in a small increase in overall school budget for the next year, which unions said was too small given average inflation has been at double-digit rates.

The government and parliament have approved measures to cut the fiscal deficit to 2.2% of gross domestic product next year, from 3.6% this year.

"We have to halt the rise in debt and the recovery package is a clear path to that," Fiala told a news conference shown on Czech Television. "It is necessary and there is nowhere to retreat from that.

"This is about political ambitions of unions and their leaders."

Teachers have been granted a pledge to have salaries at 130% of the national average, seeing a significant rise in recent years, and the strike did not call for higher teacher salaries.

The Czech Republic was spending 3.1% of gross domestic product from public budgets on primary and secondary education in 2020, slightly below the OECD average of 3.3%, OECD data showed. (Reporting by Jan Lopatka, editing by Ed Osmond)