Ontario's opposition parties are pushing forward with an investigation into the controversial cancellation of gas plants, which could lead to a finding the Liberal government was in contempt of parliament.

Premier Kathleen Wynne had sought to reach a compromise with the opposition over the thorny issue, which dominated the last legislative session in the fall, to no avail.

The Progressive Conservatives, with the backing of the NDP, voted Wednesday to have the legislature's justice committee determine whether the Liberals deliberately tried to hide documents related to the facilities.

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The government put the brakes on plants in Mississauga and Oakville at a cost of at least $230-million in what was widely seen as a political play to save Liberal seats in the 2011 election. Last September, in response to opposition demands, the government released 36,000 pages of paperwork on the matter. The following month, they turned over 20,000 pages more, which they said had accidentally been missed in the first search.

The opposition, however, alleges the documents were withheld in a deliberate cover-up.

"Misleading the House is a serious charge," PC MPP Todd Smith said Wednesday.

"We need to determine, and it is an open question at this point, if documents were destroyed in the course of this matter," said NDP MPP Peter Tabuns.

Government house leader John Milloy called the motion "mean-spirited" and argued against it.

"There was no political involvement or interference by the former minister, myself or political staff with the search [for documents]," he said.

The Tories rejected Ms. Wynne's compromise – which would have seen a special committee investigate the decision to cancel the plants themselves – because they said it would not have allowed a probe into the alleged cover-up, and that the premier would have compelled them to drop their contempt motion.

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Ms. Wynne said she was "disappointed" with the outcome before heading in to Question Period..

"My hope would have been that we could have moved on to talk about other things," she said.

The justice committee could be set up within days. It will likely question those involved in the gas plant cancellations in public hearings. Ms. Wynne has said she would appear before the committee to answer questions, but maintains she took no part in the decision to stop the plants.