Mainstream historians say up to 200,000 women were forced to work in Japanese military brothels during World War II.
Japan should do more for victims of wartime sexual slavery, UN rights experts said at a hearing on Friday, insisting Tokyo had yet to provide full redress and reparations.
Mainstream historians say up to 200,000 women, mostly from Korea but also other parts of Asia including China and the Philippines, were forced to work in Japanese military brothels during World War II.
During a two-day review of Japan's record before the UN Committee on the Elimination of Racial Discrimination, which ended on Friday, committee members criticised the nation for not focusing enough on the victims.
"I think it is a wound that has been festering for far too long," Gay McDougall, one of 18 committee members, told the assembly.
It is a wound that has been festering for far too long
The head of the Japanese delegation meanwhile insisted his country had atoned enough, after offering numerous apologies and compensation.
"The government of Japan recognises that the comfort women issue was an afront to the honour and dignity of a large number of women," Ambassador Junichi Ihara told the committee.
While strongly disputing the use of the term "sex slaves", he stressed that Tokyo had issued "its most serious apologies and remorse" to the women, including through "letters from successive prime ministers".
He also said Tokyo had "extended its maximum assistance" to a fund set up to offer medical and other support as well as "atonement money" to the former comfort women "to offer (them) realistic relief."
And he pointed to an agreement reached between Japan and South Korea in December 2015, stressing that "both countries confirmed that the comfort women issue was resolved, finally and irreversibly."