Mexico City - Mexican drug cartels are offering cash rewards for those who kill police officers as part of a campaign to scare off security forces, Mexican media reported Friday.

Some weeks ago, in the northeastern Mexican state of Baja California, leaflets circulated offering 5,000 dollars to anyone who could prove that they had killed a police officer, while killing a commander of federal forces paid 15,000 dollars, the Mexican daily El Universal reported.

A wave of violence has left over 1,100 dead - including 45 military and police officers - in Mexico since January.

"I have been in the (security force) corporation for almost 20 years and I had never seen anything like what is happening now. Criminals have lost all respect for police," one regional security officer said without revealing his name.

The Public Security Ministry recommended to high officials operating in high-risk areas like the northern states of Sinaloa, Chihuahua, Tamaulipas and Baja California to keep a low profile.

Mexican President Felipe Calderon has stressed that murders are an organized crime strategy to intimidate and create an atmosphere of terror in the face of the crackdown on drug cartels by security forces.

Since Calderon was inaugurated as president in December 2006, over 3,000 people have been killed by organized crime gangs, according to police reports. The figure is over 4,000 according to a permanent commission in congress. (dpa)