Unions claim that nearly 90 per cent of about 20,000 secondary school employees were on strike on Wednesday, while the education ministry put the figure at 75.77 per cent.
A high turnout is expected in elementary schools too because the Croatian Teachers Union has members in 800 of the 836 elementary schools, about 32,000 of a total of 39,000 employees.
The Independent Science and High Education Employees Union will join in the strike on Friday. This union's members account for over 10,000 of a total of 16,500 employees in this branch.
Said three unions want the government to compensate over the next several years for the fact that their members' salaries lag behind those in the economy by some 20 per cent.
The request is supported by five smaller education workers' unions, making this the first general strike in Croatia's education system.