MORELIA — President Andres Manuel Lopez Obrador defended his strategy on Tuesday for fighting the violent crime racking Mexico, as relatives mourned 13 police officers killed in an ambush claimed by a powerful drug cartel.

The brazen attack on Monday on a police convoy in the restive western state of Michoacan underlined the Lopez Obrador administration's struggles to rein in crime since the leftist leader took office last December.

The state police were on their way to execute a warrant in the city of Aguililla when gunmen in armored four-by-four trucks opened fire on them.

The gunmen left a series of signs with threatening messages signed by the Jalisco New Generation drug cartel, one of Mexico's most brutal.

Relatives of the officers sobbed over their coffins on Tuesday at a shared funeral service in the state capital, Morelia, some holding their now fatherless babies over the dark brown caskets.

Many erupted in anger when Governor Silvano Aureoles addressed the ceremony, shouting, "Justice!"

In Mexico City, the president called the attack "deplorable," but defended his strategy to fight the drug-fueled violence that has plagued Mexico for years.

Lopez Obrador's security plan is built around a new National Guard, which is gradually taking civilian police duties back from the military.

The government deployed the army in 2006 to fight the country's powerful drug cartels. But many experts blame the "drug war" for spiraling violence in Mexico, as fragmented cartels fight each other and the army.

"We're going to continue with our strategy," Lopez Obrador told a news conference.

"I'm optimistic, I believe we are going to achieve peace in this country.... It's a process, we're moving forward."

He repeated his pledge to fight crime at its roots by improving living standards for Mexico's poorest, and blamed previous administrations for "trying to fight violence with violence."

More than 250,000 people have been murdered in Mexico since the army was deployed to the streets in 2006, including a record 33,749 last year.

With 23,063 murders as of August, 2019 is on track to again break the country's homicide record.

The federal government initially said 14 officers were killed in the Aguililla attack, but state authorities put the toll at 13. — AFP