US president Donald Trump has threatened to close the border with Mexico to trade if Mexico does not stop immigrants from reaching the United States.

“We’ll keep it closed for a long time. I’m not playing games. Mexico has to stop it,” Mr Trump said on a visit to Florida on Saturday (AEDT).

Asked if he would close the Mexican border to all trade, Mr Trump told reporters: “It could be to all trade”.

US President Donald at Lake Okeechobee and Herbert Hoover Dike at Canal Point in Florida where he said he would close the southern border ‘for a very long time’. Photo: AAP

Mexican Foreign Minister Marcelo Ebrard shrugged off Mr Trump’s threat in a Twitter post that emphasised the countries’ ties.
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“Mexico does not act on the basis of threats. We are a great neighbor,” Ebrard posted.

“(Ask) the million and a half Americans who chose our country as their home, the largest community of (Americans) outside the U.S. For them we are also the best neighbor they could have.”

Mexican Foreign Minister Marcelo Ebrard said on Twitter on Friday that Mexico does not act on the basis of threats after U.S. President Donald Trump threatened to close the U.S.-Mexico border if Mexico does not stop illegal immigration. pic.twitter.com/CWEdZzZDfT

— Srbija Evropa (@srbija_eu) March 29, 2019

Mr Trump has repeatedly vowed to close the US border with Mexico during his two years in office.

However, this time the government is preparing to follow through as it struggles to deal with a surge of asylum seekers from countries in Central America, many of whom travel through Mexico to the border.

The DEMOCRATS have given us the weakest immigration laws anywhere in the World. Mexico has the strongest, & they make more than $100 Billion a year on the U.S. Therefore, CONGRESS MUST CHANGE OUR WEAK IMMIGRATION LAWS NOW, & Mexico must stop illegals from entering the U.S….

— Donald J. Trump (@realDonaldTrump) March 29, 2019

Department of Homeland Security officials warned that commerce with Mexico, the US’ third-largest trading partner, could slow down as the agency shifts 750 border personnel from ports of entry to help process asylum seekers who are turning up between official crossing points.

“Make no mistake: Americans may feel effects from this emergency,” Homeland Security Secretary Kirstjen Nielsen said in a statement.

Mr Nielsen and other US officials say border patrol officers have been overwhelmed by a dramatic increase in asylum seekers, many of them children and families, fleeing violence and economic hardship in El Salvador, Honduras and Guatemala.

Asylum seekers lined up at the El Chaparral border crossing in Tijuana in Mexico. Photo: Mark Abramson: The New York Times

Border patrol officers apprehended 66,450 people at the southern border in February, two and a half times the number they apprehended in February 2018.

It is not clear how shutting down ports of entry would deter asylum seekers, as they are legally able to request help as soon as they set foot on US soil.

-AAP