US President Donald Trump has threatened to deploy the military and close the southern US border if Mexico does not halt a caravan of Central America migrants heading north, raising the risk of huge disruptions to trade.
The 3,200 km US-Mexican border is one of the busiest in the world, processing thousands of commuters daily and much of the half-a-trillion dollars of annual trade between Mexico and the United States.
"I must, in the strongest of terms, ask Mexico to stop this onslaught - and if unable to do so I will call up the U.S. Military and CLOSE OUR SOUTHERN BORDER!" Trump wrote on Twitter.
Several thousand Honduran migrants moved this week through Guatemala, and some were trying to cross to Mexico on Thursday, local media said.
Some hope to eventually enter the United States to escape violence and poverty.
Mexico's government said it had sought assistance from the United Nations refugee agency to deal with migrants claiming refugee status at Mexico's southern border, one day ahead of a visit by US Secretary of State Mike Pompeo to Mexico City.
Mexican President-elect Andres Manuel Lopez Obrador, who takes office in December, said on Thursday that he believed "an agreement can be reached" on the migration issue.
"We're going to take care of our relationship with the United States government," he said. "It's very important to have a relationship of friendship."
Trump told a political rally in Montana on Thursday night that he wanted "to thank the Mexican government because they are stopping it hopefully before it ever gets to Mexico."
In the caravan, Central American migrants hiked from Honduras through muddy jungle and residential streets, some toting babies along with backpacks, Reuters images show.
In Guatemala City, where migrant shelters filled with people, waves of people departed at daybreak on roads leading to Mexico. The nearest border is about 177 km away.
"If we don't get across, we're going to try the same thing again," said Gustavo Perez, a Honduran builder speaking at a shelter in Guatemala City.
"We hope that in this big caravan group, they let us in," he added, referring to the United States.
Trump, who has vowed to curtail immigration and build a border wall on the US-Mexico border, threatened this week to halt aid if Central American governments did not act.
Frustrated by Congress' failure to fully fund his proposed wall, Trump in April ordered National Guard personnel to help secure the border in four southwestern US states.
In a string of tweets, Trump also said the border issue was more important to him than the new trade deal with Mexico to replace the North American Free Trade Agreement.
Australian Associated Press
