British soldiers and airmen who helped to operate a secretive US detention facility in Baghdad that was at the centre of some of the most serious human rights abuses to occur in Iraq after the invasion have, for the first time, spoken about abuses they witnessed there.

Personnel from two RAF squadrons and one Army Air Corps squadron were given guard and transport duties at the secret prison, the Guardian has established.

And many of the detainees were brought to the facility by snatch squads formed from Special Air Service and Special Boat Service squadrons.

Codenamed Task Force 121, the joint US-UK special forces unit was at first deployed to detain individuals thought to have information about Saddam Hussein’s weapons of mass destruction. Once it was realised that Saddam’s regime had long since abandoned its WMD programme, TF 121 was re-tasked with tracking down people who might know where the deposed dictator and his loyalists might be, and then with catching al-Qaida leaders who sprang up in the country after the regime collapsed.

Suspects were brought to the secret prison at Baghdad International airport, known as Camp Nama, for questioning by US military and civilian interrogators. But the methods used were so brutal that they drew condemnation not only from a US human rights body but from a special investigator reporting to the Pentagon.

A British serviceman who served at Nama recalled: “I saw one man having his prosthetic leg being pulled off him, and being beaten about the head with it before he was thrown on to the truck.”

On the 10th anniversary of the invasion of Iraq, a number of former members of TF 121 and its successor unit TF6-26 have come forward to describe the abuses they witnessed, and to state that they complained about the mistreatment of detainees.

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