A caravan carrying up to 2,000 migrants was forced to turn back after Mexican officials stepped in and blocked the highway.
According to reports, the migrants from Africa, the Caribbean and Central America had departed from Tapachula towards the US border.
The group, including people pushing children in strollers, proceeded on foot about 30 km before 500 members of Mexico's National Guard military police blocked them in Huehuetan.
Mexican officials reportedly sent most of the migrants on buses back to Tapachula, with 150 of them deciding to return on foot.
In June, Mexico had struck a deal with the US to significantly curb US-bound migration in return for relaxed tariffs on their goods.

Wave of bomb threats afflict European flights for third time this week
Jay Rockefeller, heir to famed dynasty and former US Senator, dies at 89
At least two children killed in bus crash in eastern France, authorities say
Vance repudiates Iran war after US electoral defeat
Malaysia ex-PM Najib Razak set for house arrest after party pays fine to leave jail
