TORONTO -- The Progressive Conservatives said Thursday they would ask the Ontario Provincial Police to investigate the destruction of government documents by senior Liberal staff in former premier Dalton McGuinty's office as theft.

"My intention is to actually phone the (OPP) commissioner and report a crime," said PC energy critic Vic Fedeli.

Police must investigate the conclusions of Ontario's privacy commissioner, who found the chiefs of staff in McGuinty's office and the Ministry of Energy broke the law by deleting emails on cancelled gas plants in Oakville and Mississauga, added Fedeli.

"The decision by premier McGuinty's office to remove electronic records from government computers and put them onto USB sticks needs to be investigated by the OPP," he said.

"These vital records are government and taxpayer property, and until they are returned they should be considered stolen."

The Tories and New Democrats accuse the Liberals of destroying emails to hide the true cost of cancelling the two gas plants, which has grown to an estimated $585 million, well above the government's original claims of $230 million.

"As in all scandals, whether it's Watergate or others, the lie becomes almost bigger than the original sin," said Fedeli. "Now in this case the original sin is $585 million of taxpayers' money, so that's a pretty big sin to get over."

The Conservatives went on the attack against Premier Kathleen Wynne during question period, insisting the police should investigate the premier's office.

"Premier, since you won't acknowledge any wrongdoing, will you at least get out of the way when the OPP comes to your office to get to the bottom of this scandal on behalf of the people of Ontario," asked Tory Rob Leone.

Wynne bristled at the suggestion she wouldn't fully co-operate with police.

"I take offence at the suggestion that I would not," the premier told the legislature.

"I would absolutely comply with anything that I was asked to do by police, and I think the member opposite actually knows that."

Wynne didn't dispute the privacy commissioner's finding that the emails on the cancelled gas plants should never have been deleted by Liberal staffers.

"I agree with her conclusions that this should not have happened," she said. "I have committed to making changes to ensure that all staff follow the rules."

The New Democrats said Wynne can't wash her hands of the problem by saying she's changed practices to make sure political staff know their obligations on document retention since she took over from McGuinty.

"I know for sure, or at least I believe that the premier has known about this all along," said NDP Leader Andrea Horwath.

"I don't believe for a minute that she took the reins of power of this party without knowing all along what had been done in terms of the cover-up."

Government Services Minister John Milloy dismissed suggestions that voters were owed an apology for the Liberals' intentional destruction of gas plant documents.

"I think what people are owed is the fact that we're not going to allow this to happen again," said Milloy.

"We will be taking action to make sure that the rules are properly enforced."

The Conservatives also called on the NDP to vote against the budget next week to defeat the minority Liberals, saying only a change in government will help get to the truth about the cancelled gas plants.

However, the NDP warned an election would kill the justice committee hearings into the gas plants, where they say the truth is slowly coming out.

"Our first responsibility is to do what's right for people back home and that's what we did in the budget, we got concessions that are important for people like a 15 per cent cut in auto insurance," said NDP house leader Gilles Bisson.

Privacy Commissioner Ann Cavoukian reported Wednesday that McGuinty's former chief of staff, David Livingston, tried as late as January to have email accounts for several Liberals permanently deleted from government databases.

The opposition parties say the Liberals cancelled the unpopular gas plants to save seats in the 2011 election, when they were reduced to a minority government.