TORONTO -- Ontario's Opposition says the Progressive Conservative government's planned 10 per cent tuition cut will not turn out to be good news for students.

An announcement is set for Thursday and government documents show the province will mandate the drop in tuition for colleges and universities, but the NDP wonder what else is coming.

Colleges and universities critic Chris Glover says he is deeply concerned that Ontario Student Assistance Plan grants will be cut.

The previous Liberal government increased the number of grants and made it possible for students with the greatest financial need to attend college or university free of cost.

But the auditor general found last month that costs for that program jumped by 25 per cent and warned it could grow to $2 billion annually by 2020-21.

The Tories are in the midst of trying to trim a deficit they peg at $14.5 billion -- though the financial accountability officer says it's closer to $12 billion.

The current tuition fee framework, which has capped increases for most programs at three per cent, expires at the end of this academic year, and the Progressive Conservative government will formally announce a new one on Thursday.

Under the new framework, tuition would decrease by 10 per cent for the 2019-2020 year, then be frozen for the following year.

The government says that means the average university arts and science undergraduate student would save about $660 and the average college student would save $340.

Core operating grants to post-secondary institutions are contingent on their compliance with the framework.

International student tuition fees aren't regulated and are not included in the cut.