British special forces must “uphold the same standards” as other soldiers in wartime, a senior defence figure said after accusations that a rogue unit killed Afghan civilians.
The Special Air Service Regiment has come under the spotlight after emails were released suggesting its troops were involved in the deaths of 33 Afghan people in 11 night raids on homes in 2011.
The Ministry of Defence said it had thoroughly investigated the claims and found no evidence to prosecute any soldiers.
But the level of detail in the emails has raised concerns over the conduct of the troops in Helmand province during the conflict.
Tobias Ellwood, chairman of the Defence Select Committee, told The National that any new evidence should be pursued by investigators.
“The British Armed Forces have one of the most highly respected reputations in the world because of their standards and values on the battlefield," Mr Ellwood said.
"If evidence comes to light that we have fallen beneath those standards, then it’s imperative that the military police reopen the investigation.”
Afghan war in pictures
The issue is expected to be discussed by Ben Wallace, the British Defence Secretary, and senior officials this week after the High Court ordered the release of the secret emails in a case brought by human rights law firm Leigh Day.
Documents seen by The Sunday Times newspaper reveal one incident in which it was alleged that a British soldier killed four people in Helmand on February 16, 2011.
SAS soldiers arrived by helicopter at night in a village called Gawahargin, in southern Helmand province, looking for a suspect behind a bombing.
Women and children were rounded up and the troops went into a family home where gunshots were heard.
A teenager named Saifullah went back into the house and found his father, brothers and cousin with bullet holes in their heads.
The allegation was passed on to the special investigation branch of the Royal Military Police, who believed the claims were serious enough to launch an investigation in 2014.
They found emails between special forces personnel, which have now been released by the court.
In one document, an SAS sergeant-major said in an email: “Is this about … latest massacre? I’ve heard a couple of rumours.”
In response, a SAS soldier wrote that the men appeared with either AK-47 weapons or hand grenades and were shot.
In one note written on the day of the killings, a British officer said he had had a “very difficult” meeting with an Afghan colonel.
One of his soldiers was a relative of Saifullah and said the dead men were teachers and farmers, not Taliban supporters.
The colonel said his men reported that nobody had fired at the coalition forces but the civilians “were shot anyway”.
“He suggests that two men were shot trying to run away, and that the other 2 men were 'assassinated' on target after they had already been detained and searched,” he said.
Concerns were also raised after 33 other deaths of which 10 were near-identical, where a captured male family member who was in his empty home to clear the way for a search, picked up a weapon and attacked the soldiers in “clearly impossible odds”.
The Ministry of Defence said the case had been independently investigated and subjected to four reviews.
“This is not new evidence," it said. "These documents were considered as part of the independent investigations, which concluded there was insufficient evidence to refer the case for prosecution.
"The Service Police and the Service Prosecuting Authority, of course, remain open to considering allegations should new evidence, intelligence or information come to light."