More than 2000 people are suing the liberal Asahi newspaper to demand that it place international advertisements apologising for its coverage of wartime sex slavery, saying it has stained Japan's reputation, local media said on Thursday.

The move is the latest salvo in the battle over Japan's history, which pits an increasingly aggressive revisionist right wing against an ever-more cowed mainstream that accepts the country's guilt over its World War II atrocities.

South Korean women who served as sex slaves during World War II protest outside the Japanese embassy in Seoul in 2011. Credit:AFP

The group of plaintiffs, including Japanese nationals living in the United States, filed the class action in the Tokyo District Court on Wednesday, according to Japanese newspapers, including the Asahi.

They argued that the Asahi's historical reports on the so-called "comfort women" system were instrumental in forging global opinion that the Japanese state and its military were involved in organising a formalised system of sex slavery.