SINN FÉIN last night expressed alarm that a British firm contracted to help process census information has links with Iraq’s notorious Abu Ghraib prison.

The company whose employee told investigators that he and military intelligence operatives directed prison guards to keep prisoners in Iraq's Abu Ghraib prison awake for as much as 20 hours a day has launched an internal investigation into activities at the prison.

A private interrogator accused of abuses at Iraq’s notorious Abu Ghraib prison has told investigators that he and military intelligence operatives directed prison guards to keep Iraqi prisoners awake for as much as 20 hours a day.

The Pentagon is pursuing five separate investigations into claims that Iraqi prisoners were abused.