But in the drug violence-wracked northern border state of Tamaulipas, state officers receive on average about 3,618 pesos, or $262 per month. Officers in the far-less-violent central state of Aguascalientes receive five times more than that.

Some of the best-paid state and local police are in the northwestern border state of Baja California, while some of the lowest-paid police are in the southern part of the country.

The report urged lagging states and municipalities to raise police wages. Low salaries have been cited as one cause of police corruption.

On Saturday, federal prosecutors detained the police chief of Ciudad Lerdo in northern Durango state and 39 of his officers for questioning in connection with the disappearance of a federal police officer on July 10.