TORONTO -- Ontario's Liberals were forced Tuesday to explain why they want to sell Hydro One after condemning the previous Progressive Conservative government for proposing a similar privatization plan.

The Conservatives dug up a 2002 quote from veteran Liberal Jim Bradley, now the chair of cabinet, saying Hydro One "is best kept in public ownership and public hands." He was debating a motion that was supported at the time by several Liberals who now are members of Premier Kathleen Wynne's cabinet.

"They were selling 100 per cent with no conditions placed on it at all when those comments were made," Bradley said. "It's pretty sad when they have to go far back in history to deal with those things, but it's all part of politics."

Bradley cited cabinet confidentiality when asked if he had ever spoken against Premier Kathleen Wynne's plans to sell 60 per cent of the giant transmission utility to raise an estimated $9 billion.

"I always support government policy," he said.

Wynne has pledged to use $4 billion from the sale to help pay for a $130-billion, 10-year infrastructure and public transit program, and $5 billion to pay down hydro debt.

"It is critical that we invest in the roads and the bridges and the other large infrastructure across the province that is needed by communities in order for them to be able to thrive," she told the legislature.

Wynne said unlike the old Tory privatization proposal, the Liberal plan will see taxpayers remain as the largest single shareholder of Hydro One.

"It was extremely important for the government and the people of Ontario to retain 40 per cent ownership, making sure we retained control of the board...and making sure that no entity could own more than ten per cent."

Wynne also raised the issue of the Conservatives' decision to privatize Highway 407 just before the 1999 election to help balance the province's books, which critics say cost taxpayers millions of dollars in lost revenues.

"One of the guiding principles that we held on to as we went into this process was that we would not do what had been done by that party with the 407," she said.

New PC Leader Patrick Brown warned that "anyone who sells one of their largest revenue tools is headed toward bankruptcy."

Brown said he won't be tied to positions taken by previous PC leaders, and warned that privatizing Hydro One will drive up electricity rates and remove oversight at the utility by the provincial ombudsman.

"The premier has lost the trust of families in Ontario because of her fire sale of Hydro One," he said. "By turning her back on independent oversight, the premier has lost the province's trust."

The New Democrats have consistently opposed any move to privatize Hydro One, and dismissed Wynne's explanation about needing money from the sale to invest in infrastructure.

"It must be sadly embarrassing to be the only premier in the history of this province who can't keep Hydro One public while at the same time investing in infrastructure for the people of Ontario," said NDP Leader Andrea Horwath.