The head of Amnesty International's Mexican branch is taking Quebec Premier Philippe Couillard to task for his comment Monday that Mexico's human rights record is moving in the "right direction."

"I beg to differ (that) Mexico is going in the right direction," Perseo Quiroz, Amnesty's executive director in Mexico, told The Canadian Press.

Couillard offered his assessment during a joint news conference with Mexican President Enrique Pena Nieto, who was in Quebec City to kick off three days of carefully choreographed North American leader summitry.

Pena Nieto was scheduled to dine with Prime Minister Justin Trudeau later Monday in Toronto before hitting the national capital on Tuesday for an official state visit.

The Mexican president will then join Trudeau and U.S. President Barack Obama for Wednesday's North American Leaders' Summit in Ottawa, commonly known as the Three Amigos.

Amnesty has been working to keep the human rights issue front and centre as the three leaders seek a public display of economic co-operation -- likely centred on climate action -- as a counterpoint to the trade protectionism and anti-immigrant sentiment that has marked this year's U.S. presidential race.

But the Mexican president was forced to confront the carnage from his country's decade-old war on drugs that Amnesty says has left 27,000 Mexicans unaccounted for, or "disappeared."

Last week, a group of female Mexican human rights activists urged Trudeau to push Pena Nieto on rights issues, citing a high level of sexual abuse of women by Mexican security forces.

Pena Nieto defended his country's plan to tackle corruption and human rights abuses on Monday.

"Our government has made an important effort to advance issues related to human rights," he said in Spanish, without elaborating. "We still have work to do. However, I think we are moving in the right direction towards having human rights being fully respected (in Mexico)."

Pena Nieto has pushed legislative reforms, but it simply hasn't been enough, said Quiroz.

"The problem with Mexico is the gap between what the law says, and what happens, is really big."

Couillard said human rights is an important topic for Quebecers, and one he raised with his guest.

"He has assured me, as he did with you a few minutes ago, that he is taking the right and appropriate actions now at the structural level to deal with the issue, which I think is also important for him and his government," the premier said.

"I think he has set the boat in the right direction, but of course this will take time and he needs the support of his allies to go forward and succeed."

Quiroz characterized Couillard's handling of the issue as merely "scratching the surface."

Rights issues are expected to take a back seat to pressing economic concerns in this week's meetings.

Britain's shocking referendum vote Thursday to remove the country from the 28-member European Union has rocked international markets and destabilized Europe, providing a sharp international contrast to this week's expected North American love-in.

Experts say it will be in Obama's interest, as well, to broaden the North American relationship in hopes of cementing his environmental policy legacy and insulating NAFTA from political mischief.

Donald Trump, the presumptive Republican presidential nominee, has advocated tough new immigration policies, border defences and possible new trade barriers, while Democratic rival Hillary Clinton is expressing reservations about the Trans-Pacific Partnership trade pact.

Trudeau and Obama have already established a warm personal relationship that appears to transcend the usual Canada-U.S. niceties, but the American president is entering the final half year of his administration and may be looking to lock in some of his policy gains, particularly on the environmental front.

In March, during Trudeau's state visit to Washington, Canada and the United States agreed to cut methane emissions 40 to 45 per cent below 2012 levels by 2025.

Methane is a highly potent greenhouse gas -- about 84 times more potent over a 20-year time frame than carbon dioxide, according to the Pembina Institute -- and also among the cheapest ways to cut GHGs, since methane is a marketable byproduct of oil and gas production and storage.

Getting Mexico into a common North American methane reduction agreement would help anchor March's bilateral deal and be good for the environment.