UPDATE 1-Truckers face gridlock at U.S.-Mexico frontier as border agents moved

Trucks delivering goods from Mexico to the United States are facing up to eight hours of gridlock, after a transfer of U.S. border agents to immigration duties slowed the flow of commercial traffic at several border crossings. President Donald Trump took a step back on Tuesday from his threat to close the U.S. southern border to fight illegal immigration, amid pressure from companies worried that a shutdown would inflict chaos on supply chains. He had threatened on Friday to close the border this week unless Mexico acted to curb a surge of asylum seekers from countries in Central America.

But the reshuffling of border agents, announced last week to process the record number of migrant families entering the United States from Mexico, prompted delays of up to eight hours for trucks crossing from Mexico's Ciudad Juarez to El Paso, Texas, truckers told Reuters. "Industry is most affected by this situation, due to the millions in fines they have to pay when deliveries arrive late to clients," said Manuel Sotelo, head of the truckers union in Ciudad Juarez. He said the delays could even lead to the cancellation of contracts and layoffs.

Senior U.S. Department of Homeland Security officials said on Tuesday that the recent redeployment of some 750 officers on the border to deal with a surge in migrants - mostly Central American families turning themselves into border agents - led to the slowing of legal crossings and commerce at ports of entry. Mexico's foreign minister, Marcelo Ebrard, also noted that commercial traffic at the U.S.-Mexico border had slowed at several crossings due to the transfer of U.S. border agents.

Ebrard said the U.S. government has told Mexico that so far it is not going to shut down the border, but said his country will be prepared for that possibility if it comes to pass. (Reporting by Jose Luis Gonzalez in Ciudad Juarez and Lizbeth Diaz in Mexico City; Writing by Anthony Esposito; Editing by Frank Jack Daniel and Leslie Adler)