TORONTO -- The union representing Ontario secondary school teachers says talks with the provincial government and the school boards are at an impasse.

The Ontario Secondary School Teachers Federation issued a statement on Saturday that two days of talks with a mediator have failed to make any progress.

Union president Paul Elliott accuses the government of continuing to demand concessions that he says would lead to inferior learning conditions for students.

The union plans to apply to the provincial labour ministry for conciliation -- the teachers must first use the government third-party assistance to try to reach a contract before they can take provincewide strike action.

Teachers are on strike in Peel, Durham and the Sudbury-area Rainbow school districts that have left more than 70,000 thousand students out of class.

But the school boards and the teachers union have been fighting for weeks on whether those walkouts are legal and Ontario's labour board is set to rule this week on their legality.

This is the first round of negotiations under a new bargaining system the Liberal government introduced last year, separating the process into local and central talks.