In the most sensational acts against national security, gunmen killed 15 federal police officers in separate attacks in two states known for heavy narcotics trafficking. In the mountainous state of Michoacan west of Mexico City, mafia assassins blocked a major highway with buses and ambushed a convoy of federal police returning to the capital, killing 12 officers and wounded at least eight.

Calder?n defended the fight against organized crime in an editorial printed in newspapers across the country on Monday.

"If we remain with our arms crossed, we will remain in the grip of organized crime, we will always live in fear, our children will have no future, there will be more violence, and we will lose our freedom," he said.

Calder?n wrote that Mexico would be in a much worse state if his administration had not decided to take on the criminal gangs. It is a battle that is supported by the Obama administration and Congress, which has dedicated $1.3 billion in aid to train police and reform courts, and supply drug-sniffing dogs, armored cars, night-vision goggles and, soon, Black Hawk military helicopters.

Monday's death toll included 29 prisoners from rival gangs who attacked each other with pistols, an assault rifle and knives in a jail in the western state of Sinaloa, home to Joaquin "El Chapo" Guzman, a billionaire cartel boss and one of the most-wanted fugitives in Mexico and the United States. Forbes magazine recently listed him as one of the richest men in Mexico.

Prison officials said 18 inmates were killed in initial assaults, and 11 died of stab wounds and beatings when fighting spread to other cellblocks.