The lower house of Congress passed the reform promoted by President Andres Manuel Lopez Obrador's ruling party by 339 votes to 154, after a heated debate Wednesday that continued late into the night.

The plan has already been endorsed by the Senate.

Before coming to power in 2018, Lopez Obrador had vowed to send the military back to the barracks.

But under his presidency, the armed forces have kept their role in tackling cartel-related violence and even gained more responsibility, including control of ports and customs and major infrastructure projects.

Amnesty International has voiced alarm at what it called "the process of militarization of public security in Mexico."

The latest reform comes amid a scandal over a huge leak of classified military files obtained by a group of hackers called Guacamaya, who have targeted several Latin American countries.

The leaks left Mexico's military facing allegations that some of its members have links to drug cartels, that it spied on the government's opponents and engineered a reform giving it control of the National Guard, which was previously under civilian command.

"How are we going to give more power to the military if the hacked documents show that some of them have ties to crime and have protected human rights violators?" opposition lawmaker Salvador Caro asked during the debate.

Accusations that the armed forces were involved in the disappearance of 43 students in 2014 -- one of the country's worst human rights tragedies -- have added to the controversy.

In August a truth commission said that the military shared "clear responsibility" for what it called a state crime, either directly or through negligence.