US sniper 50 calibre rifle
An SAS sniper used a .50 calibre Barrett rifle to kill ISIS fighters. The weapon (pictured here used by a US Army sniper) was originally designed to cripple vehiclesUS Army photo by Spc. Luke Thornberry

An SAS sniper reportedly shot through a brick wall, which was one kilometre away, to kill three Islamic State (Isis) fighters during the battle for Ramadi last week. The sniper was part of a team of British special forces embedded with and advising the Iraqi army.

Sources told the Daily Star that Isis (Daesh) fighters were using a two-storey house as a command post to launch suicide attacks. Air strikes and rocket attacks were considered to take out the militants, but it was believed that civilians were being held on the lower floor as human shields.

"A staff sergeant in charge of one of the SAS teams working with the Iraqis came up with the idea of shooting through the wall," said a source. "It was a case of 'there's nothing to lose.' If it worked the suicide attacks would be stopped – if it failed nothing would be lost."

The sniper positioned himself 1,000m away, but had a clear line of sight and fired 30 armour piercing rounds into the wall with a semi-automatic Barrett Light .50 calibre rifle, which can destroy lightly armoured vehicles and aircraft.

A defence source told the Daily Star that when SAS and Iraqi troops took the building later that day, they found the bodies of three IS fighters. "The bodies of the Islamic State fighters had been absolutely pulverised," said the source, "One had been decapitated and another had been cut in half. It was a real scene of carnage, but the tactic had proved incredibly effective. The lives of around 20 civilians had been saved."

The Iraqi army retook control of Ramadi's city centre on 27 December but continues to fight pockets of resistance around the city. Ramadi was captured by IS in May 2015 in what was considered a huge embarrassment from the Iraqi army after soldiers abandoned their posts.