TORONTO - The Liberals are using their new majority to block attempts to get to the bottom of two of their biggest scandals involving cancelled gas plants and the Ornge air ambulance service, Ontario's opposition parties charged Tuesday.

The Progressive Conservatives and New Democrats want the justice committee to call two more witnesses into the Liberals' decision to cancel two gas plants before the 2011 election, at a cost of up to $1.1 billion.

They want to hear from former Dalton McGuinty staffer Laura Miller and her computer tech boyfriend, Peter Faist, about the wiping of hard drives in the premier's office during the transition period to Kathleen Wynne's administration.

"There are two key people who know the most about who deleted emails, why there was unauthorized access to the premier's office and the destruction of documents," said PC energy critic John Yakabuski.

"Both of them have agreed to testify before this committee, and there's only one person that is holding this up, and that's the premier herself."

The NDP called blocking the last two witnesses that the opposition parties want to hear from unacceptable, and said it flies in the face of Wynne's oft-repeated commitments to lead a more open and transparent government.

"It's very disconcerting," said NDP Leader Andrea Horwath.

"Once again we have a premier who likes to hold up this mantle of transparency and yet here's a very important test of that and the Liberals are getting ready to make sure those witnesses don't come forward."

Wynne punted the questions about the gas plant hearings to government house leader Yasir Naqvi, who said that after more than two years and 90 witnesses it's time for the committee to write its report, which means no more testimony.

"The premier made it very clear that she wants the justice committee to complete its work by engaging in report writing, so they can provide recommendations to the government around record management, around siting of large energy infrastructure," Naqvi told the legislature.

The opposition parties dominated the justice committee until the Liberals won a majority in the June 12 election, so the government now controls the agenda and doesn't want any more public hearings on the cancelled gas plants in Oakville and Mississauga.

The opposition parties also called on the Liberals Tuesday to release the report of another committee that was looking into financial irregularities and other problems at the province's troubled Ornge air ambulance service.

That committee had actually written its report but never had a chance to table it in the legislature before the election was called.

"Premier, whether your minister accepts responsibility for failing in her oversight is one thing, but completely sidelining a report that could prevent future tragedies and mismanagement is unacceptable," said deputy PC leader Christine Elliott.

"We owe it to the front-line responders here, to the pilots, the paramedics and the dispatchers at Ornge who came forward."

The New Democrats wrote Wynne last week warning the Ornge report would be destroyed unless she agrees to have it tabled in the legislature.

"Many mistakes were made at Ornge," wrote NDP critic France Gelinas. "Admitting a mistake is the first step in making sure it does not get repeated."

Frank Klees, a frustrated former Tory MPP who did not run for re-election, leaked a copy of the Ornge report to the media before the election, but Elliott said she's not sure if that was the final report from the committee.

"It needs to be officially tabled so that their recommendations can be considered and acted upon," she said.

"My hope is that this Liberal government does not let another report sit on a shelf and gather dust like all the other government reports."

Ontario Provincial Police are conducting separate investigations into Ornge and the deletion of government documents related to the cancelled gas plants.

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