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MONTEBELLO, Quebec, Aug 20 (Reuters) - U.S. President George W. Bush met the leaders of Canada and Mexico at a luxurious cedar chateau on Monday to bolster economic and security ties, but protesters decried the gathering’s secrecy and shouted for Bush to go home.

Dubbed the “Three Amigos summit,” the two-day meeting of Bush, Canadian Prime Minister Stephen Harper and Mexican President Felipe Calderon was also expected to look at the credit crunch and turmoil gripping global financial markets.

One uncertainty concerning the summit’s schedule arose as Hurricane Dean threatened to batter Mexico’s Yucatan Peninsula, raising speculation that Calderon might leave Canada early.

Mexican officials said there were no immediate plans for Calderon to return home but they were looking into it.

Canada and Mexico have been frustrated that growth in trade among the partners to the North American Free Trade Agreement, or NAFTA, has been held back by the U.S. crackdown on the border following the Sept. 11 attacks in 2001.

To try to tackle that problem, the countries have developed the Security and Prosperity Partnership, or SPP. But the agenda has upset activists on the left and the right who contend it will erode national sovereignty.

As Bush and Calderon arrived at the resort in Montebello, Quebec, more than 2,000 demonstrators descended on the village as well and squared off with police in riot gear.

Some were dressed in black with their faces covered by kerchiefs. They banged on drums and chanted, “Arrest the criminals inside the fence” and “George Bush go home.”

But Harper dismissed the demonstrations. “I’ve heard it’s nothing. A couple hundred? It’s sad,” the Canadian prime minister said just before leading Bush into the log-cabin resort.

Further raising the ire of the summit’s critics is a 3-metre (10-foot) fence put up around the hotel to keep protesters at bay.

Protesters said the talks were being carried out behind the backs of ordinary citizens and without any votes planned in the Canadian Parliament or U.S. Congress. They also criticized plans for consultations with corporate leaders.

“I particularly oppose war criminal Bush seeking to annex Canada and Mexico, to put the armed forces and police services under U.S. command. It’s all very dangerous,” said Dean Lawveri, 39, of New York state.

Late in the day, a small group of protesters began to hurl rocks, bottles and cans at police, who fired tear gas to break up the crowd.

HURRICANE STIRS UNCERTAINTY OVER SCHEDULE

Calderon had been scheduled to spend an extra day in Canada, visiting with Harper in the Gatineau hills in Quebec and then addressing a business lunch in Toronto, but there was speculation he could cut his visit short.

Forecasters said Hurricane Dean had the potential to be catastrophic and it was expected to hit Mexico’s border with Belize early on Tuesday.

Bush and Calderon were meeting for the first time since legislation to overhaul U.S. immigration policies collapsed in Congress, in a blow to an issue of key concern to Mexico.

The Bush administration has moved to increase scrutiny and set heftier fines on businesses that hire illegal immigrants.

Bush and Calderon were also expected to discuss a package of hundreds of millions of dollars in aid the United States is considering for Mexico to help fight drug cartels, but a deal was not expected to be announced at the summit.

A senior Canadian official told reporters that Harper and Bush, in a one-on-one meeting, discussed Canada’s role in Afghanistan, and the Canadian leader reiterated that any future role for Canada in Afghanistan would need the endorsement of parliament.

Harper is keen to discuss Canada’s concerns about Russia’s symbolic laying of claim to the North Pole, where it placed a flag on the seabed. (With reporting by Caren Bohan and Randall Palmer in Ottawa and Alister Bell in Mexico City)