Japan has notified the UN that the imperial government in Tokyo had nothing to do with forcing women into sexual slavery for its troops during World War II.

The denial follows the signing of a deal with Korea on the issue last month whereby Japan offered a vague apology and pledged 1 billion yen in reparations.

But Tokyo's official position, long discredited by expert opinion, is that the military brothels were run by private operators and the women were simply prostitutes.

The fresh denial came in response to a question by the UN Office of the High Commissioner for Human Rights ahead of the 63rd meeting on abolishing discrimination against women.