Mexico City (CNN) -- Mexico's National Human Rights Commission has opened an investigation into reports that some indigenous communities in the country continue to practice the ancestral custom of selling their daughters.
The commission named the Highland Mixtec community in the southern state of Oaxaca as one group in which girls between the ages of 11 and 15 are allegedly sold by their parents.
"The parents have found a way to negotiate and in exchange for money give away their daughters, either to their future husbands or families who take them to other cities to help in domestic labor," the commission said in a news release.
The commission did not say how widespread the practice is believed to be or how it was alerted to it.
The girls are sold for up to 3,000 pesos (U.S. $245) or the equivalent in goods such as cattle, beans or corn, the commission said. The parents give up all rights over the girls.
Hugo Aguilar Ortiz, deputy secretary of indigenous affairs in the state of Oaxaca, said he had not heard any reports of child-selling.
Aguilar, who is himself a Highland Mixtec, said, "Where I'm from, this is not a practice, you see."
When Mixtecs get married, it is a customary obligation for the family of the groom to offer money or cattle and other products for the wedding festivities and to help the new couple start out, but this tradition does not include minors and is hardly selling, he said.
The Mixtecs are the second-largest indigenous community in Oaxaca, and the term Highland Mixtec represents a disparate and varied group of people, Aguilar said.
The state's human rights office said that it did not participate in the investigation of the child-selling claims but that the national commission does its own investigations.
The state human rights office has never received a complaint alleging the sales of girls, spokesman Juan Pablo Ceja said.
The national commission says it respects the autonomy of Mexico's indigenous communities as long as their practices do not violate the country's constitution in the area of human rights.
"In harmony with the customs, the defense and safeguard of the human rights of indigenous women is of vital importance, based on respect to their dignity, their culture and their freedom," the commission said.
According to the country's Commission for the Development of Indigenous Peoples, there are almost 10 million Indians in Mexico, about 9.5% of the country's population. About 1.5 million indigenous people live in Oaxaca state.