The latest tussle in the ideological battle between Japan's nationalist right-wing and its liberal mainstream saw the committee of academics, journalists and business leaders split on the use of the word "aggression", according to minutes released on Monday.
For Tokyo's neighbours -- its wartime adversaries -- the term is a crucial marker of Japan's acceptance of its wrongdoing in the 1930s and 1940s as it marched across Asia, leaving millions dead in its wake.
Japanese Prime Minister Shinzo Abe is expected to make his statement later this year on the 70th anniversary of the end of World War II.
His language is being closely watched by China and South Korea for any signs of backsliding by Japan.
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Beijing and Seoul vociferously argue that Tokyo has not properly atoned for its actions in the 1930s and 1940s, and does not fully accept its guilt, insisting that a landmark 1995 statement expressing remorse must stand.
"As a result of Japan's war in the 1930s through to 1945, many Asian countries became independent... But I think it is wrong to say that Japan fought the war for the emancipation of Asian countries," he said, according to the minutes.
"Japan caused many casualties in Asia in its reckless warring."
Beijing estimates that around 20 million Chinese died during the Sino-Japanese conflict.
In 1995, then-Prime Minister Tomiichi Murayama said Japan felt "deep remorse" and offered a "heartfelt apology" for its "colonial rule and aggression".