Young male prisoners were filmed being sodomised by American soldiers at the Abu Ghraib prison near Baghdad, according to the journalist who first revealed the abuses there.
Seymour Hersh, who reported on the torture of the prisoners in New Yorker magazine in May, told an audience in San Francisco that "it's worse". But he added that he would reveal the extent of the abuses: "I'm not done reporting on all this," he told a meeting of the American Civil Liberties Union.
He said: "The boys were sodomised with the cameras rolling, and the worst part is the soundtrack, of the boys shrieking. And this is your government at war."
He accused the US administration, and all but accused President George Bush and Vice-President Dick Cheney of complicity in covering up what he called "war crimes".