Seoul, June 23 (IANS): Twelve South Korean victims of Japan's wartime sex slavery on Tuesday said they will take Japan to a US federal court unless Tokyo apologises by the end of June for the atrocities done to them.

The 12 victims plan to lodge a civil suit at the US District Court in San Francisco on July 1 unless Japan demonstrates sincere intent to make amends for its crimes during the Second World War, Ahn Shin-kwon, director of the House of Sharing, a shelter housing the victims.

They would seek $2 million each for the wartime atrocities committed by Japan and its companies "and their continued denial of instigating them," Ahn said.

The shelter decided to take the case to the U.S. because previous attempts to solve it in South Korea or Japan have failed, Yonhap News Agency reported.

The defendants include the family members of then Japanese Emperor Hirohito, Japanese Prime Minister Shinzo Abe, Japanese firms that enslaved Koreans for forced labour during the war and Sankei Shimbun daily, which has called former sex slaves "prostitutes" in its articles, Ahn said.

Historians estimate that more than 200,000 women, mostly Koreans, were either kidnapped or deceived by the Japanese into working at their frontline military brothels during the war.

Two of the plaintiffs -- Kim Soon-deok and Choi Seon-sun -- have passed away since the home started filing the document, so they will be represented by their sons, Yang Han-seok and Wang Sang-mun, respectively, Ahn said.

All of the plaintiffs are above the age of 80.

The South Korean government has 238 sex slaves on file and of those, only 50 are still alive.