Many of the migrants who departed from Tapachula, Chiapas, early on Saturday had been waylaid in the city just north of Guatemala for weeks or months, awaiting residency or transit papers from Mexican authorities.

The migrants are originally from Central America, Africa and the Caribbean.

They left their home countries sometimes because of violence or simply in search of a better life.

So far, Mexican authorities have not attempted to block the advance of the group, which was trudging along a highway toward Arriaga under the supervision of human rights officials and federal police.

Australian Associated Press