Trump says he may tie NAFTA to Mexican immigration control

President Donald Trump threatened to make Mexican immigration control a condition of a new NAFTA agreement on Monday, saying the southern U.S. neighbour must stop illegal immigrants from getting into the United States.

"Mexico, whose laws on immigration are very tough, must stop people from going through Mexico and into the U.S. We may make this a condition of the new NAFTA Agreement," Trump wrote in a Twitter post. "Our Country cannot accept what is happening!"

The U.S. president made similar comments linking NAFTA, an acronym for the North American Free Trade Agreement, and immigration when a "caravan" of migrants moved through Mexico this month. "They must stop the big drug and people flows, or I will stop their cash cow, NAFTA," Trump wrote in an April 1 Twitter post.

However, discussion of immigration controls has not been a part of formal negotiations on the new NAFTA accord and talks by all accounts - including Trump's - are progressing.

Mexican Foreign Minister Luis Videgaray dismissed Trump's comment in his own Twitter post. Mexico decides its immigration policy in a sovereign manner, he said, and it would be "unacceptable" to condition the renegotiation of NAFTA.

Since peaking at about 1,500 people, the so-called caravan of migrants from Central America has dwindled under pressure from Trump and Mexican migration authorities, who vowed to separate those migrants with a right to stay in Mexico from those who did not.

One group of several hundred migrants had made it to the northern Mexican state of Sonora and could reach the U.S. border by Tuesday or Wednesday.

"If members of the "caravan" enter the country illegally, they will be referred for prosecution for illegal entry in accordance with existing law," Homeland Security Secretary Kirstjen M. Nielsen said in a statement on Monday.

She urged people seeking asylum to register with the first "safe" country they enter, including Mexico.

Before Trump's tweet, Mexican President Enrique PenaNieto, said he hoped for agreement soon on a reworkedNAFTA, which includes Mexico, the United States and Canada.

Speaking at the Hanover trade fair in Germany,Nietosaid differences between the parties could be overcome to revamp the 24-year-old accord, which underpins some $1.5trillion in annual trilateral trade.

Progress on autorules

Canada's Foreign MinisterChrystiaFreelandtold a newsconference in Toronto that she would be travelling to Washingtonon Tuesday to meet with Mexican Economy MinisterIldefonsoGuajardoand U.S. Trade Representative RobertLighthizer.

"We have for the past few weeks been involved in intensivenegotiations. This is a phase of very, very energetic work by
Canada and we will be continuing that at the ministerial level in Washington," saidFreeland.

Guajardoand others have said aNAFTAdeal could be possibleby early May, and officials hailed progress made on the keyissue of new automotive sector rules last week.

Even so, differences still remain on U.S. demands to changedispute resolution mechanisms, and other issues.