The top US commander in Iraq authorised prisoner interrogation tactics including the use of dogs, stress positions and isolation, according to a memo.

A US Army investigation found systematic abuse and possible torture of Iraqi prisoners at a base near the northern city of Mosul, just as top military officials became aware of abuse allegations at Abu Ghraib, documents show.

Fresh claims of a prisoner abuse cover-up in Iraq, Afghanistan and at Guantanamo Bay hit the US military today.