British troops in Afghanistan killed more than 50 detainees and unarmed men under suspicious circumstances, newly obtained military reports and an investigation by the British broadcaster BBC showed on Monday.

BBC Panorama program, which is to be aired on Tuesday night, looked into documents of operations by the Special Air Service (SAS) – a British elite unit used in special operations – and found they include "reports covering more than a dozen ‘kill or capture’ raids carried out by one SAS squadron in Helmand in 2010/11."

Individuals who served with the SAS squadron on that deployment talked to the program and said they witnessed the SAS operatives "kill unarmed people during night raids," according to a BBC News report.

According to the former soldiers’ account, an individual’s murder was justified by planting an AK-47 assault rifle at the scene and some individuals within the force "were competing with each other to get the most kills."

The report also alleges that "internal emails show that officers at the highest levels of Special Forces were aware there was concern over possible unlawful killings but failed to report the suspicions to military police despite a legal obligation to do so."

The investigation by the BBC suggests that "one unit may have unlawfully killed 54 people in one six-month tour."

Gen. Sir Mark Carleton-Smith, the former head of U.K. Special Forces, was "briefed about the alleged unlawful killings but did not pass on the evidence to the Royal Military Police, even after the RMP began a murder investigation into the SAS squadron."

Carleton-Smith, who retired last month as head of the British army overall, declined to comment to the BBC program "Panorama," which said its investigation was based on court documents, leaked emails and its own journalists' travel to sites of the operations in Afghanistan.

The Defense Ministry said the Panorama program "jumps to unjustified conclusions from allegations that have already been fully investigated," adding that the investigation into incidents alleged in the program did not find sufficient evidence to prosecute.

"No new evidence has been presented, but the service police will consider any allegations should new evidence come to light," it said in a statement to the BBC.

After-action reports showed other officers were surprised at the high casualty rate being inflicted by the unit, when none of the SAS troops reported injuries in apparent firefights with Taliban soldiers.

"Too many people were being killed on night raids and the explanations didn't make sense. Once somebody is detained, they shouldn't end up dead," one senior officer at special forces headquarters told Panorama.

"For it to happen over and over again was causing alarm at HQ. It was clear at the time that something was wrong."

In 2014, the Royal Military Police launched an investigation into more than 600 alleged offences by British forces in Afghanistan, including a number of killings by the SAS squadron. But RMP investigators told the BBC that they were "obstructed" by the British military, and the investigation ended in 2019.