Premier Kathleen Wynne is leaving the door open to a new tax to combat climate change, just months after saying a carbon tax was not part of the Ontario government's plan.

After winning a majority government last June, Wynne said a carbon tax was not something the Liberals planned to introduce, even though she wanted a new plan to reduce greenhouse gas emissions.

The province could adopt a cap-and-trade system that lets the worst polluters buy credits from companies that burn less fossil fuels, or impose a tax on all carbon emissions, including gasoline burned by automobiles.

When pressed today about following British Columbia's lead and imposing a carbon tax, which included a seven-cent-a-litre levy on gas, Wynne refused to rule out the idea.

The premier said she wasn't prepared to say what options the province may come up with, but added Ontario must do its part as part of a national strategy on climate change.

Wynne said Ontario wants to balance its desire for economic growth with the need to lower greenhouse gas emissions.

Environment Minister Glen Murray is preparing a report on the various options to put a price on carbon emissions.

Ontario committed to carbon pricing in 2008 when it signed the Western Climate Initiative with California and Quebec, which have since created a joint cap-and-trade system.

Wynne spoke about supporting cap-and-trade during a joint cabinet meeting with Quebec Premier Philippe Couillard in November.

"We've been supportive of cap-and-trade process for many years, and we are continuing to have that discussion with Quebec," she said at the time.