ZAGREB, Croatia (AP) — Thousands of state school teachers in Croatia have rallied in the capital Zagreb to demand higher wages, after expanding an ongoing strike last week to affect schools nationwide.

Carrying banners and blowing whistles, protesting teachers and their supporters filled Zagreb’s main square on Monday, pledging to carry on with their open-ended strike until their demands are met.

Unionists say teachers’ salaries are lagging behind those of other public employees. Talks with the government are planned later Monday.

The strike started last month and was initially held on certain days of the week in a limited number of municipalities. But last week it was expanded nationwide and made open-ended to increase pressure on the government.

Union leader Sanja Sprema said strikers “are fighting for the future of our children.”