COPENHAGEN, Denmark - If the Canadian government ends up with a weak deal in Copenhagen to tackle climate change, the provinces could ignore it and take stronger action, says Quebec Premier Jean Charest.

"In Copenhagen, the federal government has the power to sign treaties, but it doesn't have the power to bind provincial governments to them," Charest said Wednesday.

"That's the Canadian reality, and it's a hard reality."

Ottawa wants to cut Canada's greenhouse gas emissions by 20 per cent from 2006 levels by 2020. But some provinces, including Quebec and Ontario, say that plan doesn't go far enough.

Ottawa fires back

Federal Environment Minister Jim Prentice shot back at Charest, saying the federal government has the authority to represent Canada as a whole.

"Canada doesn't need the approval of the provinces to establish or conclude a treaty," Prentice said. "Our federation couldn't function if, at every international conference, we need unanimity from the provinces."

Regardless, a successful outcome from the Copenhagen climate change summit looked doubtful Wednesday. The Danish president of the conference, Connie Hedegaard, has resigned and will be replaced by the Danish prime minister as head of the talks. UN climate chief Yvo de Boer says Hedegaard will continue to lead informal talks but Prime Minister Lars Loekke Rasmussen will now be the formal head of the conference.

Protests

As officials struggled to come to a deal, protesters battled police outside the meetings.

Police were using tear gas, pepper spray and batons to disperse crowds of protesters trying to disrupt the talks on Wednesday. Police spokesman Per Larsen says 230 protesters have been detained in the clashes outside the suburban conference centre.

With reports emerging that summit talks have become deadlocked, the protesters say they want to take over the conference and turn it into a "people's assembly."

Harper's office occupied

Meanwhile, about 20 environmental activists occupied Harper's Calgary constituency office Wednesday and called for Canada to take a tougher position on climate change in Copenhagen.

The sit-in is the eighth such event to target Conservative cabinet ministers, some of which have resulted in trespassing charges.

With files from The Canadian Press