Thousands of Honduran migrants whose trek toward the United States has triggered a series of tirades from US President Donald Trump resumed their long march after crossing a river into Mexico.

Donald Trump says "full efforts" were underway to halt the caravan's progress toward the United States.

Nevertheless, around 3,000 people were marching in the caravan on the Mexican side, according to an estimate from a federal police commander whose forces were closely monitoring the migrants' progress.