Mexico City (AFP) - Mexican President Enrique Pena Nieto said Friday troops will remain in the streets to combat drug violence after his defense minister issued a rare complaint about the controversial deployment.

Although Pena Nieto acknowledged that the soldiers and marines have been doing law enforcement tasks that "don't correspond to them in the strictest sense," he said the armed forces are "determined to continue" policing the streets.

The military deployment has allowed "cities and regions in our country to return to peace and calm," he said.

Defense Minister Salvador Cienfuegos said on Thursday that the military "didn't ask" to be fighting criminals.

"We don't like it. We didn't study how to chase criminals," the general 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."

Mexico marks 10 years on Sunday since then president Felipe Calderon deployed for the first time thousands of troops to combat drug cartels.

The deployment has led to the capture of major drug lords but soldiers and marines have been accused of committing torture and other abuses over the years.

Violence also soared in the years that followed as the arrests of drug bosses sparked turf wars in several regions.

Pena Nieto, who took office in 2012, has said that troops would return to their barracks once citizens feel safe across the country.