MEXICO CITY — The top prosecutor in Mexico’s state of Veracruz confirmed Tuesday that more than 250 skulls have been found in what appears to be a drug cartel mass burial ground on the outskirts of the city of Veracruz.

State Prosecutor Jorge Winckler said the clandestine burial pits appear to contain the victims of drug cartels killed years ago.

‘‘For many years, the drug cartels disappeared people and the authorities were complacent,’’ Winckler said, in apparent reference to the administration of fugitive former governor Javier Duarte and his predecessors.

In an interview with the Televisa network, Winckler did not specify when the skulls were found or by whom. But they appear to have been found over the course of months.

Victims’ advocacy groups like Colectivo Solecito have excavated — and pressed authorities to excavate — such sites to find missing loved ones.

The skulls and other bones were found in an area known as Colinas de Santa Fe, where activists have been exploring since at least mid-2016, sinking rods into the ground and withdrawing them to detect the telltale odor of decomposition. When they find what they believe are burial pits, they alert authorities.

Winckler said excavations have covered only a third of the lot where the skulls were found, and more people may be buried there.

Associated Press