Canadian Foreign Minister Chrystia Freeland said on Tuesday that NAFTA trade talks between the United States, Canada and Mexico should be trilateral, saying that approach was common sense.

Speaking at an event in Mexico City, Freeland said that Canada supported Mexico's strategy to diversify trade away from dependence on the U.S. market and that Canada was moving in the same direction as well.

Mexico's Foreign Minister Luis Videgaray also said on Tuesday that it would be very difficult to reconcile the NAFTA framework in bilateral deals, adding that elections next year in Mexico would make talks more difficult and he called for starting negotiations as soon as possible.

But he warned that Mexico, the United States and Canada could "shoot ourselves in the foot" if they tweak rules too much and drive investment elsewhere.

Under these rules, manufacturers must obtain a minimum percentage of components for their products from Canada, Mexico or the United States.

U.S. President Donald Trump has threatened to leave the North American Free Trade Agreement if it cannot be reworked in favor of U.S. workers, and his administration last week set the clock toward a mid-August start of renegotiation in a letter to the U.S. Congress.

Mexico sends the vast majority of its exports north to the United States, and local officials view the trilateral treaty as a lynchpin of their economy.

On Monday, the head of Mexico's automakers' association told Reuters that the auto industries of the three NAFTA nations agreed there should be no changes to current rules of origin.

Guajardo also said it was key for Mexico, the United States and Canada to set clear goals early before starting what are likely to be "roller coaster" NAFTA talks, with days of good and bad news.

U.S. Trade Representative Robert Lighthizer said on Sunday that the United States favors bilateral over multilateral trade deals, though he said last week that NAFTA talks would be trilateral.

Videgaray agreed, saying it would be hard to reconcile the frameworks of NAFTA in bilateral deals.