The migrants, who are mostly from Honduras, are ultimately trying to reach the United States, despite President Donald Trump's threat that the military would be called to the US-Mexican border if the "onslaught" is not stopped.

READ MORE: Migrant caravan using women & children as human shields to break into Mexico – Pompeo

Organizers say that some 4,000 migrants form part of the caravan that arrived at Mexico's border on Friday. Photos showed the bridge between the two countries packed full of people, with many resorting to jumping in the river below after being blocked by Mexican riot police.

The reported green light for women and children comes after many migrants were sent back on Saturday, with Guatemalan police transporting at least 62 people in two buses.

Honduran President Juan Orlando Hernandez is due to meet his Guatemalan counterpart Jimmy Morales in Guatemala City on Saturday for talks on a strategy to return the Honduran migrants.

DETAILS TO FOLLOW