Former Premier Dalton McGuinty should answer questions about deleted emails relating to the gas plant scandal, says Ontario premier Kathleen Wynne.

McGuinty stepped down as MPP for Ottawa-South Wednesday, saying he was leaving politics with his "idealism intact and a deep sense of gratitude for the opportunity to have served in public life."

"The fact that he's stepping down as MPP and he will make that announcement today, that doesn't mean he can't be called before the committee and can't answer further questions," Wynne told Craig Norris on The Morning Edition Wednesday.

"I encourage anyone who has been asked to come and speak at the committee that they do that, and that certainly has been my advice to Dalton and any of his staff," she said.

A justice committee is holding hearings into cancelled gas plants in Oakville and Mississauga, a move which has cost an estimated $585 million. Wynne voluntarily testified before the committee in April. McGuinty testified in May.

But the NDP is now pushing for McGuinty appear before the committee again after a report by Ontario’s privacy commissioner Ann Cavoukian found that senior staffers in McGuinty's office intentionally deleted emails about the gas plant decision.

The Ontario Provincial Police have opened an investigation into deleted emails pertaining to the cancellation of the two gas plants since the report was released.

 Wynne maintains she wasn't aware of the fact that staffers were deleting emails related to the gas plants.

"I think [McGuinty] has spoken in recent days about the rigour or lack of rigour around document retention but again you'll have to speak to him about the specifics because I wasn't in those conversations and I certainly wasn't part of those instructions," she said.  

"I acknowledge that mistakes were made. You know there were things that happened that absolutely should not have happened," said Wynne.

3 seats now empty in Ontario

McGuinty's resignation from his Ottawa-South seat after 23 years as the Liberal representative leaves a total of three empty seats in the Ontario legislature.

Byelections must be called by the middle of August in Windsor and London to replace former Finance Minister Dwight Duncan and former Energy Minister Chris Bentley.

They both resigned after Wynne won the Liberal leadership in January.

The Tories have been pushing for a general election, saying Ontario needs a fresh start.

Wynne said she wants to avoid calling a provincial election pre-emptively in the coming months, but would not rule one out.

"In politics, you never say never," said Wynne.

"That's one of the rules. But I have no intention of calling an election in the immediate future, none whatsoever."