TORONTO -- Premier Dalton McGuinty and senior Liberal cabinet ministers "lied" to the legislature when they repeatedly said all documents on cancelled power stations in Oakville and Mississauga had been released last month, PC Leader Tim Hudak charged Monday.

"We've had now several occasions where they have actually lied to MPPs," Hudak told reporters at a news conference.

"We commonly don't use that kind of language in the legislature, but I don't know what else to call it."

Another 20,000 pages on the cancelled energy projects were released late Friday, weeks after McGuinty and his cabinet ministers kept insisting all relevant documents were released last month, as required by a Speaker's ruling.

"It's apparent that for weeks the government knew that the documents hadn't been released, and so it's obvious that they were keeping information, yet again, from the people of Ontario and from the legislature," said NDP Leader Andrea Horwath.

"The most important thing here is to acknowledge the premier had a role here, and he's refusing to take responsibility for it."

Energy Minister Chris Bentley and government house leader John Milloy both rose before question period Monday to correct the legislative record, and insisted "there was no deliberate attempt" to provide incorrect information to the legislature.

"Any incorrect information provided to this House was provided inadvertently and unintentionally," said Bentley. "I'm very disappointed that the error was made."

Both the Conservatives and New Democrats asked why McGuinty wasn't making a statement to correct his own record in the legislature.

During question period, McGuinty said he and his government had been given wrong information by bureaucrats, who "in all good faith" thought they had turned over all documents on the gas plants last month.

"Officials, and only officials, were involved in the selection of documents to meet the committee request," McGuinty told the legislature.

Despite being advised Sept. 27 that officials at the Ontario Power Authority and the Ministry of Energy were conducting a second search for documents, McGuinty, Bentley and Milloy continued to say for weeks that all documents had been released Sept. 24.

The opposition parties also complained that Friday's second batch of documents "is virtually missing any correspondence or briefing materials at the political level," the same complaint they made about the first 36,000 documents.

"It just does not pass the sniff test that there are next to no emails or correspondence between the political level and the bureaucracy or between the premier's office and the minister of energy's office," said Hudak.

"I remain convinced that significant, important documents remain buried."

Horwath said the NDP also find the lack of documents from politicians unusual given the decisions were made by Liberal campaign headquarters to cancel the gas plants to save Liberal seats in the areas west of Toronto.

"The premier let his campaign team cut private power deals without even telling the energy minister," said Horwath.

"When will the premier show some leadership and make it clear he will appear at committee and when he appears he will apologize for this mess?"

The Tories said the Liberals were engaged in an "orchestrated cover up" to hide the true cost of cancelling the power plants, which the government says is $230 million but the opposition parties put at a minimum of $650 million.

The opposition complained many of the new documents were redacted, and demanded Bentley's resignation.

The Conservatives complained to the Speaker Monday that McGuinty and his ministers had "clearly" misled the legislature and moved a second contempt motion against the government.

The fight by the Tories and NDP to get the gas plant documents from the Liberals triggered a contempt motion against Bentley that derailed all other legislative business for a full week.

Despite an impassioned, last-minute plea from McGuinty the opposition parties out-voted the minority government to send the contempt motion, and the issue of the gas plant documents, to the Finance Committee, which is to begin hearings by Oct. 26.