Ontario's NDP education critic is criticizing the provincial government's decision to increase secondary school class sizes as more details emerge on the impacts of the move.

Marit Stiles says the Progressive Conservative government is "ripping opportunities right out of the hands" of students after the Toronto District School Board said it would have to cut hundreds of elective classes and support programs at secondary schools to meet the mandated class sizes.

The board says that starting in September, 547 high school electives and 187 compulsory classes for Grades 9 and 10 will either be cancelled or combined into larger classes to keep them afloat.

It says dozens of library sections as well as literacy courses, guidance support, credit recovery courses and other programs will also have to be axed because of the mandated increase of secondary school class sizes from 22 to 28 over the next four years.

Stiles says the cuts in the number of sections means classes will be "too jam-packed" for teachers to give any students one-on-one support when they need it.

The Ministry of Education did not immediately reply to a request for comment.