TORONTO - Ontario's Progressive Conservatives say a police raid to find deleted emails from senior Liberals on cancelled gas plants shows the extent of the attempt to cover up the $1.1 billion scandal.

Ontario Provincial Police executed a search warrant Wednesday looking for government computers at a storage facility as part of their investigation into deleted emails by staff in former premier Dalton McGuinty's office.

PC critic Vic Fedeli says police convinced a judge to issue a subpoena, and insists the investigation is proof that information on the cancelled gas plants in Oakville and Mississauga is still being withheld.

Fedeli says Premier Kathleen Wynne was "up to her neck" in the gas plants scandal, and needs to come clean about who ordered email accounts deleted.

Wynne's office says the premier has testified twice at the committee hearings into the gas plants, which have been going on for more than a year, and broadened its mandate to make as much information public as possible.

The Tories say the committee will keep digging until it finds out who ordered the coverup, noting it was the auditor general -- not the Liberals -- who confirmed the actual cost of the gas plant cancellations could hit $1.1 billion.