Although the abuse in Basra was carried out by a group of soldiers led by a corporal, Sir William said that senior officers bore a “heavy responsibility” for not halting the assaults.

The Defense Ministry had previously disciplined a number of the officers and soldiers involved, dismissing several from the military. On Thursday, it said it would immediately suspend any of those still serving, pending further review of their cases.

Six men were acquitted in a court-martial in 2007. A seventh, Cpl. Donald Payne, whom Thursday’s report referred to as “a violent bully,” drew a one-year prison term for subjecting Mr. Mousa to inhumane treatment. Mr. Fox, the defense minister, told Parliament on Thursday that he had instructed officials to “see if more can’t be done to bring those responsible to justice.” Mr. Mousa’s lawyers demanded that those involved be tried in civilian courts.

The parallels between the cases in Basra and the American abuse scandal at Abu Ghraib prison — including the similar techniques used and the difficulty of holding senior officers to account — have haunted many in Britain. Both involved the abuse of civilian detainees in military custody, and they occurred at roughly the same time, a few months after the 2003 invasion. During that period, American and British troops had begun to face sustained attacks by Iraqi insurgents that resulted in mounting military casualties.

At the time, British commanders in southern Iraq were often outspoken in comparing what they described to visiting reporters as their troops’ restrained and population-friendly tactics with American practices farther north. Citing Britain’s long colonial history, they said their troops understood better than American forces the counterproductive results of aggressive tactics against indigenous people.

Britain withdrew the last of its forces from Iraq in 2009, leaving American troops as the only substantial foreign military presence there. Many analysts in Britain, and some retired officers, described the six-year involvement in Iraq as a dismal failure, mostly centered on the British failure to prevent Shiite militias from gaining effective control of parts of Basra and other cities.