The leaders of North America will set a continent-wide target of 50-per-cent clean-energy power by 2025 as part of a comprehensive plan to combat global warming when Prime Minister Justin Trudeau hosts the Three Amigos summit on Wednesday.

In a White House briefing on Monday, senior U.S. officials said the leaders will also discuss how North America can insulate itself from the economic fallout of the Brexit referendum.

U.S. and Canadian officials say the leaders of Canada, the United States and Mexico will also lay out specific steps on the environment, from integration of electricity transmission lines to sweeping measures on clean energy.

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"We will announce a historical goal to achieve 50-per-cent clean power across North American by 2025," U.S. President Barack Obama's senior adviser, Brian Deese, told reporters.

"That will be through a combination of renewable energy, nuclear power, power plants using carbon-capture storage and cutting energy waste through increased efficiency."

North America currently generates 37 per cent of its energy from clean power, although Canada produces 81 per cent domestically, the United States generates 32 per cent and Mexico comes in at 18 per cent.

Mexican President Enrique Pena Nieto, who arrived in Canada on Monday, indicated that Mexico favours joining a cap-and-trade system that was established by California, Ontario and Quebec.

"Quebec is a landmark in the world, as well as Ontario and California, and it is very likely that Mexico, on its part, will do its share to be part of this carbon market," he said on his arrival in Quebec City, where he met Governor-General David Johnston and Quebec Premier Philippe Couillard.

Mexico will also sign on to a Canada-United States pact agreed to in March to cut methane gases in the oil and gas sector by 45 per cent by 2025.

"We will bring all three North American countries in alignment," Mr. Deese said. "If we achieve these goals of a 45-per-cent reduction, we will reduce approximately one million metric tonnes of methane emissions per year by 2025."

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The focus of the summit was initially to be on the environment, but U.S. officials acknowledge that significant time will now be devoted to Britain's referendum vote last week to leave the European Union, according to Mark Feierstein, senior director of Western Hemisphere affairs at the U.S. National Security Council.

"We will be eager to discuss what this means for us," Mr. Feierstein told the media briefing. "This is very much an issue for the U.K. and Europe to work out, but the President will obviously want an opportunity to discuss with Prime Minister Trudeau and President Pena Nieto how we may be able to co-ordinate our efforts to insulate ourselves to the extent possible."

Mr. Pena Nieto expressed concern about the "financial volatility" caused by the Brexit vote and heralded the advantages of free trade in North America.

"The decision to leave the EU as a result of the referendum in the U.K. for the world generates uncertainty," he told a news conference in Quebec City before flying to Toronto for a dinner hosted by Mr. Trudeau and Ontario Premier Kathleen Wynne. "We have seen how trade has increased as being part of NAFTA and that trade has generated more jobs in Canada and Mexico."

The Mexican President avoided any mention of Donald Trump, the presumptive Republican nominee for U.S. president who has vowed to rip up the North American Free Trade Agreement, and build a wall between the United States and Mexico. Mr. Trudeau has also refrained from any direct criticism of Mr. Trump, out of concern he could win the presidency.

"The one person who won't sidestep it is the President of the United States," former U.S. ambassador to Canada Gordon Giffin, an adviser to presumptive Democratic nominee Hillary Clinton, said in an interview. "He doesn't have a need to sidestep the issue."

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In his dinner remarks, the Prime Minister said the summit will look to foster "growing greater trade, creating strong growth and … looking to find common solutions to our shared challenge of climate change."

Mr. Feierstein said the summit will now be an "opportunity to highlight the significance of North America," noting that the leaders will also announce initiatives to co-ordinate on peacekeeping around the world, and measures to combat drug trafficking, a serious problem in Mexico. Canada is expected to offer intelligence and training to help Mexicans fight the drug cartels.

The three leaders will also announce a "North American caucus" to make a formal effort to co-ordinate approaches on regional and global issues. "When North America acts and speaks as a single unit, it is really for the good of our citizens" Mr. Feierstein said.

On Monday, the federal Conservative Party called for an emergency meeting of the House of Commons international trade committee to discuss the implications for the Comprehensive Economic and Trade Agreement, the trade pact between Canada and the EU that has not yet been ratified. Britain accounts for 50 per cent of Canadian exports to the EU.

"The Conservative opposition wants to ensure the government actually has a plan to get CETA across the finish line, while at the same time establishing free trade with the United Kingdom," Conservative MP Randy Hoback said in a statement.