Six-hour-long negotiations between irregular workers at schools and education authorities fell through the previous day, leading some 22,000 irregular workers at schools -- including cooks, nutritionists and administrative workers -- to stage a walkout until Friday.

As of 10 a.m. Wednesday, 22,004 irregular workers, or 14.4 percent, of those working at 10,585 public kindergartens and schools across the nation had joined the strike, according to the Ministry of Education.

A total of 2,802 of 10,438 public schools were affected nationwide.

School meal services were suspended at 2,572 schools. The students were asked to bring their own lunches or else they received bread, milk, juice or other simple food instead of hot meals. Some 230 schools cut classes short.

The irregular workers, who are permanent employees but are paid less than regular workers, are demanding equal pay, welfare benefits and job security.

They have demanded a 6.24 percent increase in their basic pay and the elimination of discrimination in allowances, as part of their campaign to achieve 80 percent of the salary level of the lowest-grade civil service employees during the Moon Jae-in presidency.

Education authorities are believed to have offered a 1.8 percent pay raise.

The education offices in 17 cities and provinces are operating situation rooms to minimize inconvenience caused by the strike and draw up measures.

The three-day strike could be extended, according to the workers.

Irregular workers in the public sector, including the striking school workers, held a rally at Gwanghwamun Square on Wednesday demanding regular employment status. Some 53,000 attended, organizers said.

By Ock Hyun-ju (laeticia.ock@heraldcorp.com)