Updated

Mexico's human rights body said Tuesday that the government shouldn't be allowing the formation of vigilante groups in areas where people are increasingly confronting drug gangs.

Raul Plascencia, president of the National Human Rights Commission, said the growth of these groups are already undermining the rule of law but could also lead to more violence. He blamed the emergence of such groups on an official failure to provide security.

"This is a failure for the government because it's not able to offer the most minimum protection," Plascencia said.

A report by the commission released Tuesday said rights workers detected at least 7,000 members of armed self-defense groups in just the southern state of Guerrero where they conducted interviews.

Vigilante groups were noted in more than half of Guerrero's municipalities, according to the report, but Plascencia said he also had received reports of similar bands in 10 other Mexican states.

Residents told the commission workers that they feel vulnerable to kidnappings, extortions and killings.

So far, the self-defense groups that have drawn the most attention are those that have sprung up in Guerrero and Michoacan, where there are clashes with alleged drug traffickers. Vigilantes have also arrested suspected criminals and resisted turning them over to the government, fearing they would be set free.

Such groups are illegal, but Plascencia said the lack of security in drug-ravaged areas is fueling the growth of vigilante groups. He also faulted authorities for helping start up some of the bands by offering members uniforms and vehicles.

Not all self-defense groups are breaking the law. Guerrero allows indigenous communities to form special forces to help authorities with community policing. But Plascencia said those groups could also pose a danger, saying they are now taking over complete control in their areas.

Plascencia said the national commission is investigating the case of one vigilante who faces kidnapping allegations.

Nestora Salgado, a U.S. citizen, was leading a vigilante police force in her hometown of Olinala when she was arrested in August. Both she and her family contend she is being held for political reasons because she opposed government corruption and violence by drug cartels.