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.

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 Masato Otaka 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."

The need for dignity 

Under that accord, Japan offered an apology and a one-billion yen ($8.6 million) payment to surviving Korean comfort women.

But critics have said the deal did not go far enough in holding Japan responsible for wartime abuses.

"I don't think that agreements between governments ... are able or adequate to extinguish the claims of individuals with regards to human rights abuses," McDougall said.

She urged Japan not to "debate the facts" of what happened, and decried a "sort of blockage ... in doing what I think is probably very simple, which is offering apology and reparations that the victims feel is adequate and that meets their needs of dignity."

Committee member Marc Bossuyt meanwhile lamented Japan's "failure to provide a fully victim-centred approach."

He called on the country to "provide an official, unequivocal recognition of responsibility by Japan for serious human rights violations committed by its military against women and girls before and during World War II." (AFP)