Mexican soldier
The Mexican army has faced a string of accusations of extrajudicial killingsDaniel Becerril/Reuters

Calls for federal prosecutors to investigate a video that appears to show a soldier shooting a civilian lying face down in the back of the head from point blank range in the central state of Puebla, Mexico, are intensifying.

Diario Cambio published security footage of the incident from 3 May in the town of Palmarito that purportedly depicts an extrajudicial killing – something the military has been implicated in before. According to reports, the night-time shooting was part of an encounter with suspected fuel pipeline thieves that left 10 people dead, including four soldiers.

The heavily edited video shows a badly damaged car rolling to a halt. Sparks can be seen flying as gunfire ricochets off the vehicle and soldiers subsequently surround it.

Two soldiers then drag a man – who appears to be alive – into a well-lit part of the street. The man can be seen lying face-down for approximately six minutes as he is surrounded by military officers.

Moments later a single gunshot is fired straight into the back of the man's head and one soldier standing by the victim lifts a leg up, as though it took him by surprise. A pool of what looks like blood then spreads across the ground.

"We were there watching TV and suddenly you heard like collisions," a man identified solely as Joaquin for fear of reprisal told the Associated Press (AP).

"All you could do was listen because we couldn't go out because it sounded really bad, the shots," he said on Wednesday (10 May). The next morning, Joaquin added, the camera that had been mounted on a security pole had vanished.

The video sparked outrage and Mexico's defence ministry said prosecutors should "comprehensively clear up" whether the video does in fact show a soldier shooting a detained man.

Mexican media identified the man who was apparently executed as Raúl Jiménez Martínez, 46.

On Wednesday, Angelica de la Peña, chairwoman of the Senate Commission on Human Rights, said the military should concentrate on international threats and not law enforcement in local communities.

"There was already concern about the use of excessive force by the military, and now this video seems to give us proof," de la Peña said in a statement.

In a statement late on Wednesday, the military said: "Conduct contrary to the law and human rights cannot be justified under any circumstances."The attorney general's office has promised to fully investigate the events in Palmarito.

The Mexican army has been implicated in extrajudicial force in the past, including the deaths of 22 alleged gang members at a warehouse in the municipality of Tlatlaya in Mexico state in June 2014.

Warning: This video contains graphic scenes which some viewers may find upsetting.