Mexico's National Human Rights Commission is protesting an assault on one of its workers in the southern state of Oaxaca.

The commission reports that the agent was abducted on a highway Sunday near the town of Jalapa del Marques while traveling to the group's local headquarters in Ixtepec.

It says the captors beat, robbed and threatened to kill the man "if he continues to harm the people-trafficking business," before letting him go.

The commission on Thursday urged authorities to investigate and punish those responsible.

The assault occurred in an area that serves as a key corridor for migrants moving through Mexico toward the United States.

In a separate statement, the rights commission warned of corruption, abuse and extortion of people held at migrant detention centers in Oaxaca and other states.