MEXICO CITY: Mexico's government still owes an explanation to the families of 43 student teachers who disappeared eight years ago, and must clear up what role the armed forces played in the crime, a top international human rights body said on Tuesday.

The Inter-American Commission on Human Rights (IACHR) said efforts by officials to cover up what happened to the students in the southwestern city of Iguala in September 2014 appeared to be part of a "structural pattern" of abuses in Mexico.

"Mexico still has an international obligation to provide a satisfactory explanation about the fate or whereabouts of the 43 college students," the IACHR, the human rights arm of the Organization of American States, said in its most recent report.

The government did not immediately reply to a request for comment.

The previous Mexican administration said the youths were murdered and their remains destroyed after they were abducted by corrupt police working with a local drug gang, who believed the students had been infiltrated by a rival outfit.

A group of experts later created by the IACHR to review the evidence picked holes in that version of events, and said the Army, which has a base in Iguala, was withholding evidence.

The administration of President Andres Manuel Lopez Obrador in August published new findings, calling the incident a "state crime" and pointing to army involvement.

Authorities later withdrew over 20 arrest warrants that had been issued against chiefly military officials.

The IACHR said despite its desire to resolve the case, the new government had failed to remove "persistent structures within the state apparatus that sought to cover up the crime."

"We're talking about the Mexican armed forces," said IACHR commissioner Esmeralda Arosemena de Troitino, raising concern about what she called the "militarization" of the country under Lopez Obrador. The leftist president has given the Army a remit that extends deep into areas usually reserved for civilians.

Relying increasingly on the armed forces even as investigators seek to hold them to account for potential rights abuses risked creating a conflict of interest, she added.

Lopez Obrador says investigations are ongoing. Investigators have so far only definitively identified the remains of two of the students. The rest are still unaccounted for.

The Washington-based IACHR has helped to shed light on human rights abuses in the Americas for more than six decades.