A judge or panel of judges is needed to get to the bottom of the gas plants fiasco and find out whether there was any criminal wrongdoing, the source told The Canadian Press.
The inquiry would identify what went wrong, who's accountable, if there's any mechanism to recoup tax dollars, the source said. It would also ensure parameters are set up so that no government can use political pressure to do it again.
"And if there's criminal wrongdoing, we'll be prosecuting it to the fullest extent of the law," the source added.
The NDP says accountability can't wait until after the next election.
"We've been clear for some time that the public who paid for this decision deserves all of the details. A public inquiry, now, not possibly after the next election, is the best way to do this," said NDP House Leader Gilles Bisson.
The Liberals admitted last week that they found a third batch of documents on the gas plants, after insisting that all the relevant data was made public months ago.
It set off another wave of outrage among the opposition parties, who have been hammering the government for months over the cancelled plants.
They've accused the Liberals of relocating the Oakville gas plant in 2010 and the Mississauga plant in the dying days of the 2011 election campaign to save Liberal seats in the face of local opposition to the projects.
Something like the Gomery inquiry into the federal Liberal sponsorship scandal would be appropriate, the source said.
Premier Kathleen Wynne won't strike a legislative committee devoted solely to examining the gas plant cancellations as promised and has released yet another batch of documents, the source said.
The Ontario Power Authority has taken the blame for the botched searches for the files. It said it "messed up some search terms" and 600 new pages were overlooked in the first two searches.
But the OPA also said it told the Ministry of Energy last November that it was conducting a third search and there "likely" would be more documents. Yet the Liberals insisted as recently as last week that all the files had already been released.
The opposition claim the third batch of documents is proof of an "immense amount of political interference" by the Liberals and there are more documents to be found, since there are still no files from the premier's office or the minister of energy.
They also believe the cancellation of the gas plants cost taxpayers a lot more than the $230 million the Liberals claim. Ontario's auditor general is investigating the costs.
Wynne has rejected a public inquiry, saying a legislative committee and an investigation by the auditor general would get to the bottom of the cancellations and the release of the documents.
"Both opposition parties said they would cancel both the Mississauga and Oakville gas plants, knowing there would be costs involved," Kelly Baker, a spokeswoman for Wynne, wrote in an email Sunday.
"The new Ontario government will continue to work with the opposition to get all the facts out ... The Auditor General and the all-party committee will achieve the same result as a public inquiry, but with less cost to Ontarians."
The Tories have already revived a rare contempt motion over the Liberals' refusal last summer to produce documents about the gas plants.
They released 36,000 pages and told the legislature that all the documents had been made public, only to produce another 20,000 pages a month later.
But the initial contempt motion died — as well as the committee's hearings — when former premier Dalton McGuinty shut down the legislature in October.
As soon as the opposition parties get close to the truth, the Liberals will do whatever it takes to shut down the investigation, the source said.
"So it's pretty clear the only one who will get to the bottom of this scandal is the next government."