John Negroponte, US deputy secretary of state, made clear Washington would not support any Japanese attempt to play down its wartime history, calling the imperial army's treatment of sex slaves during the war "most deplorable.”

His comment, during a visit to Tokyo, came a day after Shinzo Abe, Japan's prime minister, denied that the country's military had forced foreign women into sexual slavery during the second world war. "There is no evidence to prove there was coercion, nothing to support it," he told reporters on Thursday.