According to Associated Press, Mexican labour secretary Javier Lozano has ended the rescue phase of the efforts after the last body, that of a 38-year-old miner, was located early Sunday local time.

The news service said officials were looking at gas buildup underground as cause for the explosion at the small mine, owned by Binsa and located in San Juan de Sabinas in the state of Coahuila near the Texas border.

It had been open for business just 20 days.

According to CNN, Lozano told media outlets the federal government would step up mine inspections across Mexico following the incident.

"We want coal free of blood; clean coal," he said.

The first five miners’ bodies were located last Tuesday night and Wednesday. Three of them were found near the front face of the mine.

According to AP and CNN, last week’s explosion at the vertical-shaft mine was so strong that a 15-year-old boy working on a conveyor belt outside the pit was seriously injured in the blast.

He was transported to a hospital, where both of his arms were amputated.

It was that event, Lozano told AP Wednesday, which left him with little faith that anyone inside would have survived.

"The outlook is very bad," he said.

"The truth is that it does not allow us to hold out much hope."

While officials have not yet released a full list of those killed in the accident, late last week Lozano identified via Twitter the first five killed as miners Julio Cesar Resendiz Dominguez, Mario Alberto Anguiano Montes, Leobardo Sanchez Santos, Isaias Valero Perez and Juan Carlos Escobedo Chavez.

Mexican President Felipe Calderon said in a public statement shortly after the explosion the country’s government "will do everything in its power to help state and local authorities rescue the rest of the trapped miners."

A Binsa spokesperson told UPI that the mine where 25 non-unionized miners worked was in compliance with safety regulations, and denied operating in an unsafe manner.

“[Binsa] is one of the companies with the best safety,” spokesperson Jesus Espinosa said, noting that both government and union officials had reviewed operations.

Sabinas is in the heart of Mexico’s coal-producing region. The mine is one of many small operations supported in part by the Mexican state and produces coal for power generation.

The country’s worst-ever mining accident occurred in 2006, when 65 workers died in an explosion at Grupo Mexico's Pasta de Conchos coal mine.

Victims’ families are still pushing for efforts to recover 63 bodies still encased in the operation.