Now an investigation by the online magazine, Middle East Eye, has claimed British soldiers shot and killed a number of unarmed people in both countries.
The report, published on Monday, 4 February, claims two former infantrymen in the British Army who served in southern Iraq said they were told in 2007 they should shoot any individuals who were holding mobile phones or acting suspiciously.
The men reportedly said there was a widespread fear that Islamists and Iraqi nationalists opposed to British occupation of the Basra region would target UK forces and used teenage boys, known as "dickers", to carry out surveillance.
Exclusive: how British troops in Basra had a license to kill unarmed civilians https://t.co/yV1wbFwwjL— David Hearst (@davidahearst) 4 February 2019
The pair claim the normal rules of engagement were amended to allow British troops to gun down anyone suspected of keeping them under surveillance or preparing roadside bombs, known as IEDs (improvided explosive devices).
A former Royal Marine reportedly told the Middle East Eye one of his officers confessed to having shot dead an eight-year-old boy.
Another former soldier said he saw two unarmed teenage boys being shot dead in Afghanistan and said a cover-up was then staged to make it look as if they were armed with Soviet-era weapons, which had been taken from a special store within the British Army base.
"I'm fairly sure that they were being kept for that purpose. We were visited daily by troops from headquarters, and these weapons could easily have been catalogued and sent back," the man told Middle East Eye.
None of the soldiers' accounts can be verified and the UK Ministry of Defence refused to comment on the reports.
The MoD said at the time 90 percent of those complaints had been dismissed, with fewer than 10 percent still the subject of investigation by the Royal Military Police under Operation Northmoor.
In 2013 a Royal Marine, known only as Marine A, was found guilty and jailed for life by a military court of murdering an injured Afghan insurgent in 2011, in what the prosecution called "an execution".
Marine A, later identified as Alex Blackman, had his conviction overturned in 2017 and replaced by one of manslaughter on the grounds of diminished responsibility and he was immediately released.
No British soldiers have ever been convicted of war crimes related to operations in Iraq.
In 2005 Trooper Kevin Williams, 22, of the 2nd Royal Tank Regiment, walked free after the prosecution dropped a murder charge. Williams admitted shooting father-of-nine Hassan Abbad Said near Basra on 3 August 2003 but maintained he was protecting himself and a colleague, believing their lives were at risk.
Trooper Williams had maintained he was protecting himself and a colleague, believing their lives were at risk.