TORONTO -- An unapologetic Dalton McGuinty lashed out Tuesday at the justice committee looking into cancelled gas plants saying it was just a partisan effort by the opposition parties to topple the minority Liberal government.

"This is not about pursuing the truth, it's about defeating the government," the former Ontario premier said during his second appearance at the public hearings into cancelled gas plants in Oakville and Mississauga.

"I have no idea how long this committee will sit for, but something tells me it will sit until the next election because it serves your short-term political purposes."

The opposition parties say Liberal staff wiped out emails to try to cover up the cost of cancelling the two energy projects, which is at least $585 million, far more than the $230 million the Liberals originally claimed.

McGuinty also predicted a police investigation prompted by Progressive Conservative complaints about the mass deletion of emails by senior Liberal staff would go nowhere.

"The ultimate result and outcome of this investigation, I'm very confident what it's going to be: no grounds for laying any changes of any kind," he said.

"You and I understand that this is a political tactic, but many Ontarians don't understand that."

The Tories said McGuinty was out of line to say the opposition-dominated justice committee hearings were being used as a partisan tool to attack the minority Liberal government.

"That's awful," said PC energy critic Vic Fedeli.

"When we say something he alleges it's partisan, and when he throws a PC indiscretion from the past, then it's okay, so I didn't buy any of that."

The New Democrats called McGuinty "misleading and evasive" and said they suspect there was political direction to Liberal staff to wipe out their emails.

"When you see systematic destruction of documents by the people who were at the centre of this scandal, it's hard to believe that there wasn't some decision to go ahead and make sure there was no record," said NDP energy critic Peter Tabuns.

"Let's face it, all the key people who were involved with this cleared out all their records on this matter. If that isn't suspicious, I don't know what is."

McGuinty was called back to the justice committee hearings after Information and Privacy Commissioner Ann Cavoukian found staff in the former premier's office broke the law by deleting all their emails.

Liberal staff did their best to follow confusing, contradictory and murky guidelines on document retention, and the rules need to be clarified, McGuinty insisted.

"What to destroy and what to preserve is today a matter of judgment," he said.

"There's no comprehensive, exhaustive list which tells you precisely when to preserve and when to destroy."

McGuinty testified he was much more concerned with jobs, the economy and health care than with keeping track of emails.

"The premier's day is pretty full, so I don't give much thought to the Archives Act. he said. "I don't give much thought to the management of emails."

Cavoukian, who testified earlier in the day, said the legislation -- written by the Liberals under McGuinty -- is pretty clear.

"Let's start with the name of the act," she told the committee. "It's called the Archives and Recordkeeping Act, not the Record-Deleting Act."

Premier Kathleen Wynne has formally apologized for the gas plants scandal that broke under McGuinty's watch, but the former premier himself flatly refused to say he was sorry on Tuesday.

Cavoukian told legislators that it was hard to believe the Liberals deleted emails for any reason other than to block public access to the documents.

"By adopting a delete-all email policy, political staff were not addressing the requirement that government business records must be retained, with the exception of transitory, personal, constituency or duplicate records," she testified.

Cavoukian said she was surprised to learn only small fractions of the deleted emails could ever be recovered, and said her officials would meet Wednesday with the Ontario Provincial Police to discuss the situation.

"They have an entire department that is devoted to such activities, whereas I do not, and perhaps they can unearth something that we were not successful in unearthing," she said. "I think that's unlikely, but I would welcome their intervention."

The justice committee hearings into the cancelled gas plants and the slow release of documents by the Liberal government will resume in August.