Ontario Premier Kathleen Wynne will testify in the legislature next week about her party’s decision to scrap two GTA gas plants, a move that her critics say cost the province at least $1 billion.

Wynne has admitted the cancellations of the Mississauga and Oakville gas plants were political moves. She will take the stand before the legislature’s justice committee, which has been tasked with examining a contempt motion against the Liberals. A datehasn’t yet been disclosed but the committee meets next Tuesday and Thursday.

Cancelling the Mississauga gas plant alone cost $275 million, according to a report from the auditor general, $85 million more than the Liberals indicated. It happened days before the 2011 provincial election.

A report on the cost of the Oakville plant cancellation isn’t expected until August. While the Liberals had said that decision cost taxpayers about $40 million, Energy Minister Bob Chiarelli acknowledged last month that figure likely isn’t accurate.

The contempt motion claims former energy minister Chris Bentley purposefully withheld documents on the cancellation of the two power plants.