Iraq war logs: Frago 242 – a licence to torture -How the newly released US military files reveal an instruction to ignore detainee abuse by Iraqi authorities; what that meant on the ground; and just how far up the chain of command the order went guardian.co.uk

Fresh evidence that US soldiers handed over detainees to a notorious Iraqi torture squad has emerged in army logs published by WikiLeaks.

The 400,000 field reports published by the whistleblowing website at the weekend contain an official account of deliberate threats by a military interrogator to turn his captive over to the Iraqi "Wolf Brigade".

The interrogator told the prisoner in explicit terms that: "He would be subject to all the pain and agony that the Wolf battalion is known to exact upon its detainees."

The evidence emerged as the deputy prime minister, Nick Clegg, said the allegations of killings, torture and abuse in Iraq were "extremely serious" and "needed to be looked at".

Clegg, speaking on BBC1's Andrew Marr Show, did not rule out an inquiry into the actions of British forces in Iraq, but said it was up to the US administration to answer for the actions of its forces. His comments contrasted with a statement from the Ministry of Defence today, which warned that the posting of classified US military logs on the WikiLeaks website could endanger the lives of British forces.

Clegg said: "We can bemoan how these leaks occurred, but I think the nature of the allegations made are extraordinarily serious. They are distressing to read about and they are very serious. I am assuming the US administration will want to provide its own answer. It's not for us to tell them how to do that."

Asked if there should be an inquiry into the role of British troops, he said: "I think anything that suggests that basic rules of war, conflict and engagement have been broken or that torture has been in any way condoned are extremely serious and need to be looked at.

"People will want to hear what the answer is to what are very, very serious allegations of a nature which I think everybody will find quite shocking."

A Channel 4 Dispatches programme on Monday night is expected to add further details based on the logs of alleged abuse directly by coalition forces. Only two cases of alleged involvement of British troops have so far been mentioned.

Within the huge leaked archive is contained a batch of secret field reports from the town of Samarra. They corroborate previous allegations that the US military turned over many prisoners to the Wolf Brigade, the feared 2nd battalion of the interior ministry's special commandos.

In Samarra, the series of log entries in 2004 and 2005 describe repeated raids by US infantry, who then handed their captives over to the Wolf Brigade for "further questioning". Typical entries read: "All 5 detainees were turned over to Ministry of Interior for further questioning" (from 29 November 2004) and "The detainee was then turned over to the 2nd Ministry of Interior Commando Battalion for further questioning" (30 November 2004).

The field reports chime with allegations made by New York Times writer Peter Maass, who was in Samarra at the time. He told Guardian Films : "US soldiers, US advisers, were standing aside and doing nothing," while members of the Wolf Brigade beat and tortured prisoners. The interior ministry commandos took over the public library in Samarra, and turned it into a detention centre, he said.

An interview conducted by Maass in 2005 at the improvised prison, accompanied by the Wolf Brigade's US military adviser, Col James Steele, had been interrupted by the terrified screams of a prisoner outside, he said. Steele was reportedly previously employed as an adviser to help crush an insurgency in El Salvador.

The Wolf Brigade was created and supported by the US in an attempt to re-employ elements of Saddam Hussein's Republican Guard, this time to terrorise insurgents. Members typically wore red berets, sunglasses and balaclavas, and drove out on raids in convoys of Toyota Landcruisers. They were accused by Iraqis of beating prisoners, torturing them with electric drills and sometimes executing suspects. The then interior minister in charge of them was alleged to have been a former member of the Shia Badr militia.

It is unclear which US unit filed the report of complaint that detainees were being specifically threatened with being turned over to the Wolf Brigade. The entry describes the capture of prisoners near the town of Falluja, west of Baghdad.

It is headed "Alleged detainee abuse by interrogators", and reads: "On 14 December 2005, a raid was conducted whereby five individuals were detained for suspicion of emplacement of IEDs [improvised explosive devices] as a result of a pid [positive identification]. "During the interrogation process the RO [ranking officer] threatened the subject detainee that he would never see his family again and would be sent to the 'Wolf Battalion' where he would be subject to all the pain and agony that the 'Wolf Battalion' is known to exact upon its detainees."

The war logs also disclose that Wolf Brigade members were themselves at risk of reprisals. In January 2007, US soldiers reported a gruesome discovery in a street near Baghdad: "Only the severed head was found. A wire was run through the ear with the corpse's ID attached to the wire. 3rd bn [battalion] commander identified the remains as Ahdel Abu Hussain, he was an officer in the NP [national police] Wolf Brigade."

Lawyers said the reports may embroil British as well as US forces in an alleged culture of abuse and extrajudicial killings. Phil Shiner, of Public Interest Lawyers, appearing alongside the WikiLeaks founder, Julian Assange, at a press conference in London, said some of the deaths may have involved British forces and could now go through the UK courts.