LONDON: British special forces allegedly carried out a pattern of war crimes going back more than a decade to the Iraq and Afghanistan wars, former members have told the BBC.

Breaking years of silence to provide eyewitness accounts to the 鈥淧anorama鈥� investigative program, multiple veterans reported that their colleagues had killed people in their sleep, executed detainees 鈥� including children 鈥� and planted weapons to justify the murders.

The two units at the center of the reports are the British Army鈥檚 Special Air Service and Royal Navy鈥檚 Special Boat Service, the country鈥檚 top special forces units.

One SAS veteran who served in Afghanistan said: 鈥淭hey handcuffed a young boy and shot him. He was clearly a child, not even close to fighting age.鈥�

The eyewitness accounts relate to allegations of war crimes that took place more than a decade ago, far longer than the scope of a public inquiry into the allegations now being carried out in the UK, which is examining a three-year period.

The SAS veteran told 鈥淧anorama鈥� that the execution of detainees by British special forces 鈥渂ecame routine.鈥�

Soldiers would 鈥渟earch someone, handcuff them, then shoot them,鈥� before 鈥減lanting a pistol鈥� by the body, he added.

British and international law only permits deliberate killing when enemy combatants pose a direct threat to the lives of troops or other people.

An SBS veteran told the program that some troops suffered from a 鈥渕ob mentality,鈥� causing them to behave 鈥渂arbarically.鈥�

He added: 鈥淚 saw the quietest guys switch, show serious psychopathic traits. They were lawless. They felt untouchable.鈥�

The 鈥淧anorama鈥� investigation includes witness testimony from more than 30 people who served with or alongside British special forces in Iraq and Afghanistan.

Another SAS veteran said: 鈥淪ometimes we鈥檇 check we鈥檇 identified the target, confirm their ID, then shoot them. Often the squadron would just go and kill all the men they found there.鈥�

Killing became 鈥渁n addictive thing to do,鈥� another SAS Afghanistan veteran said, adding that some soldiers in the elite regiment were 鈥渋ntoxicated by that feeling.鈥�

He said: 鈥淥n some operations, the troops would go into guesthouse-type buildings and kill everyone there.

鈥淭hey鈥檇 go in and shoot everyone sleeping there, on entry. It鈥檚 not justified, killing people in their sleep.鈥�

One veteran recalled an execution in Iraq, saying: 鈥淚t was pretty clear from what I could glean that he posed no threat, he wasn鈥檛 armed. It鈥檚 disgraceful. There鈥檚 no professionalism in that.鈥�

Awareness of the alleged war crimes was not confined to individual units or teams, veterans told 鈥淧anorama.鈥�

Within the command structure of the British special forces, 鈥渆veryone knew鈥� what was taking place, one veteran said.

鈥淚鈥檓 not taking away from personal responsibility, but everyone knew,鈥� he added. 鈥淭here was implicit approval for what was happening.鈥�

In order to cover up the killings, some SAS and SBS members went as far as carrying 鈥渄rop weapons,鈥� such as Kalashnikovs, to plant at the scene of executions.

These would be photographed alongside the dead and included in post-operational reports, which were often falsified.

One veteran said: 鈥淲e understood how to write up serious incident reviews so they wouldn鈥檛 trigger a referral to the military police.

鈥淚f it looked like a shooting could represent a breach of the rules of conflict, you鈥檇 get a phone call from the legal adviser or one of the staff officers in HQ.

鈥淭hey鈥檇 pick you up on it and help you to clarify the language. 鈥楧o you remember someone making a sudden move?鈥� 鈥極h yeah, I do now.鈥� That sort of thing. It was built into the way we operated.鈥�

The investigation also revealed that David Cameron, UK prime minister at the time of the alleged war crimes, was repeatedly warned about the killings by then-Afghan President Hamid Karzai.

He 鈥渃onsistently, repeatedly mentioned this issue,鈥� former Afghan National Security Adviser Dr. Rangin Dadfar Spanta told the program.

Gen. Douglas Lute, a former US ambassador to NATO, said Karzai was 鈥渟o consistent with his complaints about night raids, civilian casualties and detentions that there was no senior Western diplomat or military leader who would have missed the fact that this was a major irritant for him.鈥�

In response to the gathering of new witness testimony by 鈥淧anorama,鈥� the UK鈥檚 Ministry of Defense said it is 鈥渇ully committed鈥� to supporting the public inquiry into the alleged war crimes. It urged all veterans with knowledge relating to the allegations to come forward.