By Adriana Barrera and Michael O'Boyle
MEXICO CITY (Reuters) - Mexican President Felipe Calderon removed his attorney general on Monday to try to revamp a war against drug cartels that have resisted an army campaign to defeat them.
Calderon told reporters that Attorney General Eduardo Medina Mora, who spearheaded the government's fight against drug trafficking, had resigned and would be replaced by a little-known former legal official.
A crackdown by thousands of troops and federal police has been unable to suppress turf wars between rival cartels that have killed more than 13,000 people since Calderon took power in late 2006.
Calderon has staked his presidency on his war on drugs, but cartels are killing about 20 people a day in Mexico -- often after torturing them -- and traffickers have infiltrated many state and municipal police forces.
A large deployment of troops in the city of Ciudad Juarez, on the border with Texas, has not slowed a wave of drug killings there.
About a dozen hooded gunmen burst into a drug rehabilitation clinic in Ciudad Juarez last week, lined up patients and shot 17 of them dead in a gang killing.
Medina Mora will be replaced by Arturo Chavez, a former official in the attorney general's office, Calderon said.
Despite making big drug seizures and capturing some cartel leaders, security forces have been unable to catch Joaquin "Shorty" Guzman, the head of the powerful Sinaloa cartel.
Mexico's most-wanted man, Guzman escaped from jail in a laundry van in 2001.
(Reporting by Adriana Barrera and Michael O'Boyle, editing by Chris Wilson)