A military judge hearing pre-trial evidence in the alleged abuse of prisoners at Abu Ghraib prison pressed the US government today to speed up its investigations, warning that delays could derail the case against at least one of the accused soldiers.

Four US soldiers charged with abusing Iraqi prisoners at Abu Ghraib prison face pre-trial hearings before an American military judge in Mannheim, Germany today and tomorrow.

Army Specialist Jeremy Sivits, who took photos of abuse at the Abu Ghraib detention centre in Iraq, described soldiers laughing and joking as they beat, stripped and sexually humiliated detainees, according to newspaper reports.