Education trade 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.
This Independent Science and Higher Education Employees Union's members account for over 10,000 of a total of 16,500 employees in this branch.
Unions claim that nearly 90 per cent of about 20,000 secondary school employees were on strike on Wednesday and Thursday, while the education ministry put the figure at 75.77 per cent.
Unionists said they would continue to strike next week, unless the government makes them an offer.