Mexico City: Tests have identified the remains of one of 43 trainee teachers abducted 10 weeks ago in south-western Mexico, a source close to the investigation said on Saturday, apparently confirming a feared massacre the government has blamed on drug gang henchmen.

The brazen attack has sent shockwaves through Mexico, shining a spotlight on the nexus between impunity, corruption and drug gangs that has blighted the country for years.

A protester with the number 43 painted on his body marches in Mexico City. Credit:Reuters

Mexican President Enrique Pena Nieto is facing his deepest crisis over his government's handling of the probe into the case of the students, who the government says were murdered and incinerated, their remains then tipped into a garbage dump and a river.

The source said that Argentine forensic experts working in Mexico had informed the family of the identified trainee teacher.