The bodies of 20 people were found near a highway bridge in Mexico’s northwestern Sinaloa state, authorities said.

According to the state prosecutor’s office on Monday, four bodies were located by the roadside, while another 16 were found inside an abandoned vehicle.

All of the victims showed signs of gunshot wounds, officials said.

Violence in the region has escalated sharply since the reported capture of Sinaloa cartel co-founder Ismael "El Mayo" Zambada nearly a year ago.

Zambada has claimed he was kidnapped by a son of jailed drug kingpin Joaquin "El Chapo" Guzman and flown against his will to the United States.

The conflict has led to deadly infighting within the cartel, pitting El Chapo’s loyalists — including his sons — against rivals aligned with Zambada.

According to official figures, more than 1,200 people have been killed in the region as a result.

The Sinaloa cartel is one of six Mexican trafficking groups designated as terrorist organisations by the United States.

Nationwide, drug-related violence in Mexico has claimed around 480,000 lives since 2006. More than 120,000 people remain missing.