In a historic ruling sure to ignite controversy, Canada's Supreme Court said Thursday that Quebec cannot secede without the federal government's consent.

The decision marked a major victory for the federal government, which had asked the court to rule on the issue. But it almost certainly will antagonize Quebec's provincial government, which favors independence, and could encourage it to hold a new referendum on it.Quebec's ruling Parti Quebecois contends that residents of the mostly French-speaking province have the right to decide for themselves whether to break away from Canada.

The high court ruling did give Quebec nationalists some grounds for satisfaction. It said federal authorities would have a duty to conduct negotiations about secession if a clear majority of Quebeckers supported independence in a fair referendum.

The federal government turned to the Supreme Court after being shaken by French separatists' near-victory in a 1995 referendum. The government hoped a favorable court ruling would convince wavering Quebec voters that secession would not be quick and painless.

The justice minister asked the court to rule on three questions. Can Quebec legally declare unilateral independence under Canadian law? Can it secede under international law? If there is a conflict, which law prevails?

The court said under Canadian law, Quebec was obligated to negotiate with the federal government and the other provinces if it sought to secede. It said international law, in regard to the establishment of new states, did not apply to Quebec's situation.

Quebec's separatist premier, Lucien Bouchard, is in a strong position politically despite the court ruling. He now can run an election campaign in the next few months claiming that Quebeckers' right to decide their own destiny is under siege.