BEIJING (Yonhap) ― China said Tuesday that it has asked UNESCO to recognize documents related to Japan’s sexual enslavement of women during World War II, as part of its bid to get Tokyo to sincerely repent its wartime atrocities.

In a faxed statement to Yonhap News Agency, China’s foreign ministry said it has submitted the documents for inclusion in UNESCO’s Memory of the World Register “to prevent such crimes against humanity from happening again.”

China has been reportedly seeking to have UNESCO recognize documents on Japan’s wartime atrocities, but it is the first time that the Chinese foreign ministry confirmed its move for the UNESCO designation for the documents on women forced into sexual slavery in military brothels run by the Japanese army in World War II.

“The documents submitted by China deserve to be on the list because they have an important historical value,” the ministry said in the statement.

The Chinese ministry did not say when it made the application, but said the documents were found in China.

In the statement, the Chinese ministry also blamed Japan for the deterioration in bilateral relations, citing Tokyo’s failure to atone for its wartime past.

“For now, China-Japan relations remain in a state of tension and all responsibility lies with Japan,” the ministry said. “Over the past years, Japan has been displaying negative attitudes by denying and whitewashing its history of aggression during World War II.”

China and Japan have also quarreled over maritime territories, but their relations have deteriorated sharply over the past two years due to an acrimonious dispute over a chain of uninhabited islands in the East China Sea.

Historians say up to 200,000 women from Korea, China and other Asian nations were coerced into sexual servitude at front-line Japanese brothels during the war. Those sex slaves were euphemistically called “comfort women.”

Japan’s nationalist politicians, including Prime Minister Shinzo Abe, have drawn criticism by arguing that there is no evidence that the women were coerced by the then Japanese government.

South Korea has also pressed Japan to address long-running grievances by the victims of wartime sex slavery by extending a formal apology and providing compensation to them. But Japan has refused to do so, saying the matter was settled by a 1965 treaty that normalized relations between the two countries.

Time is running out for those aging victims in South Korea. On Sunday, a 91-year-old South Korean victim, Bae Chun-hee, died.

Currently, only 54 victims remain alive and their average age is 88.