Mexican soldiers take part in an operation to destroy a poppy plantation in the mountains in Guerrero State (AFP Photo/Pedro Pardo)

Mexico City (AFP) - Mexico's defense minister has complained about his troops having to take part in the country's war on drug trafficking -- a rare expression of criticism about the controversial, decade-old deployment.

Speaking at a news conference, Salvador Cienfuegos insisted the military was not suited for the job.

"We didn't ask to be here. We don't like it. We didn't study how to chase criminals," he said.

"Our function is something else and it's been made into something unnatural. We are doing things that don't correspond to our training because there's no one else to do them," the minister said.

Sunday is the 10th anniversary of an order by Felipe Calderon, the conservative president in office from 2006 to 2012, that harnessed the military as the pillar of a federal anti-drug operation.

His action drew harsh criticism from the opposition and civil society organizations.

But until now, top-level military officials have not publicly expressed much about the anti-drug operation amid documented human-rights abuses.

Cienfuegos insisted the wave of criminal violence cannot be stopped "by bullets" and that he would be the first to lift "not one but both hands" to get the army back to its original mission.

Calderon initially involved the army in the anti-drug war with a deployment of 5,000 troops to his home state of Michoacan in western Mexico, where the local police were overwhelmed by drug-cartel violence.

Weighing as a possible solution professionalizing the police to allow for a gradual withdrawal of the military in the drug war, Cienfuegos pointed out that police currently lack sufficient training to fulfil their obligation to fight crime.

According to data from the National Commission on Human Rights, in the past decade more than 12,000 complaints were filed about alleged violations by the military, most of them in the anti-drug operation.

The most frequent complaints are arbitrary detentions, excessive use of force, torture, break-ins, robbery and false accusations.

Last April, a video emerged showing two soldiers and a police officer torturing a woman, leading Cienfuegos to offer an apology.

The government says that since 2006 more than 170,000 people have been killed and more than 28,000 have been reported missing. The data does not indicate which cases are related to organized crime.