The four boys between the ages of six and 13 took their clothes off in front of around 600 people in response to an offer by the organiser of the rodeo, who invited the children to participate in a "contest."

First they were told to spin around until they collapsed, and afterwards, for a few pesos, they were "dared" to take off their clothes, which four of the children did.

The incident occurred on Nov. 29 in the indigenous town of Hueytlalpan in the mountains of Puebla, which is next to the Mexican capital.

The rodeo was part of the festivities of Saint Andrew, the patron saint of the rural town of 20,000 indigenous people.

According to Irma Ramos, a Puebla legislator who was present at the event and who protested the incident while it was occurring, some people in the crowd, including Mayor Juan Martín Barrientos, laughed and made fun of the children, although others booed what was happening.

"It was certainly a kind of sex abuse, but I think many of the people there had no idea what was going on," said Sauri.

In his opinion, the incident highlights a view that is deeply rooted among many Mexicans: that the rights of children are the property of parents and local authorities, "and can be granted and taken away as they please, which is false, because those rights exist independently and are not a gift from anyone."

The most serious aspect of what happened is that the incident took place in front of the authorities, who have the responsibility of looking out for the rights of minors.

It also occurred in a state whose governor, Mario Marín, was accused in 2006 of ordering the arrest of journalist and activist Lydia Cacho, whose 2005 book "Demons of Eden" implicated businessmen close to him in an alleged child prostitution ring in the southeastern resort town of Cancún.

In February 2006, the local media aired recordings of tapped telephone conversations between Marín and businessman Kamel Nacif, the protector and close friend of a convicted pedophile.

In the conversations, the voices identified as those of Nacif and Marín discuss how they had Cacho thrown into a cell with "nutcases and dykes (lesbians)," so that she would be raped, and the governor can be heard saying he had the journalist, who he referred to as "that old b***h," arrested and taught a lesson.

After her book was published in 2005, Cacho was arrested on libel charges brought by Nacif, driven 900 kms from her home to the state of Puebla, held for 30 hours, mistreated by the police and threatened. But despite Nacif and Marín’s alleged plans, she was not mistreated by her fellow prisoners.

Marín, who belongs to the Institucional Revolutionary Party (PRI), denied the allegations against him. But experts have confirmed that the voice in the conversations illegally taped by Nacif’s wife in the midst of the couple’s divorce was the governor’s.

The governor has not personally spoken out about the case of Hueytlalpan, although spokespersons for his government condemned the incident, and both the attorney general’s office and the human rights commission of the state of Puebla have launched investigations.

Marín had a chance to somewhat redeem himself by publicly speaking out against what occurred in Hueytlalpan, and the fact that he has not done so "raises eyebrows," said the head of the Network for the Rights of Children, which groups around 70 social organisations.

Lawmaker Ramos, of the left-wing Democratic Revolution Party (PRD), who publicly denounced the incident, said she would not rest until those who were responsible are brought to justice.

On Friday, she brought legal action before the national Attorney-General’s Office. The parents of the children involved in the incident will do the same on Monday.

In her view, what happened in Hueytlalpan was an act of child pornography and pedophilia.

According to a 2004 study by researcher Elena Azaola, some 17,000 children under the age of 18 are victims of the sex trade in Mexico.