TORONTO - The New Democrats say they're being stonewalled in their efforts to find out the true cost of cancelling two gas plants in Oakville and Mississauga.

NDP critic Peter Tabuns says the Ontario Power Authority is refusing to release information about the government's cost estimates for cancelling the plants.

The party was seeking the information under freedom-of-information laws, but the OPA says all the records are exempt from disclosure.

Tabuns says if the government isn't going to come clean with the costs now, they should put them in the upcoming spring budget.

The Oakville plant was cancelled in October 2010 and the Mississauga plant was cancelled during last fall's election campaign -- sparking opposition accusations that it was a calculated move to save Liberal seats.

But the Liberals haven't said how much it will cost taxpayers, saying the OPA is still negotiating with the companies.

Both plants proved unpopular to local residents, who organized campaigns against them.