Mexico's human rights ombudsman has called for an enquiry into the public shaming of a group of teachers and administrators in the state of Chiapas.
Up to 14 administrators and head teachers were marched barefoot through the town of Comitan after they defied a strike.
A faction of Mexico's teachers' union, the CNTE, allegedly placed signs around their necks saying they were traitors.
Many of them had their heads shaved while crowds of people watched.
The ombudsman, Luis Gonzalez Perez, said protests needed to remain within the law.
Mexico's Education Secretary Aurelio Nuno said he would ensure those responsible were punished.
The teachers' union have accused "agents of the state" of infiltrating their ranks to discredit their strike action.
The BBC Mundo correspondent in Mexico, Juan Paullier, says these types of incidents are not unusual in Mexican education.
Last year, alleged members of the CNTE shaved the heads of teachers in Chiapas because they had opposed their strike action.
The CNTE has been on strike in Mexico City since 15 May and has been conducting a series of protests.
It opposes education reforms introduced in 2013 which include new measures to evaluate teachers.