The government has filed a protest against China’s applications to have what it says are historical documents on the 1937 Nanking Massacre and Japan’s wartime “comfort women” brothel system registered in the U.N. archive program, Chief Cabinet Secretary Yoshihide Suga said Wednesday.

During his daily news conference, Suga lashed out at Beijing for “politically exploiting” sensitive historical issues “when Japan and China need to make efforts to improve the bilateral relationship.”

Beijing “is trying to unnecessarily play up (the two issues). It’s extremely regrettable,” Suga said. “We filed a protest and requested (Beijing) to withdraw the application.”

Chinese Foreign Ministry spokeswoman Hua Chunying said Tuesday that Beijing filed applications to register the documents for UNESCO’s Memory of the World program.

South Korea, which also suffered under Japan’s past aggression, is considering similar steps over the comfort women who were forced to serve in Japanese-run military brothels.

In April, China made public a huge collection of previously confidential wartime documents written by Japanese military officers, including some accounts related to the women pressed into sexual servitude.

“What China has submitted for application this time are authentic, rare and precious documents with historical significance, which meet the standard of application,” Hua was quoted as saying on the ministry’s website.

“By applying for the inclusion of precious historical documents related to the Nanking Massacre and Japan’s forced recruitment of the comfort women in the register, China is to memorize the history, treasure the peace, uphold the dignity of mankind and prevent behaviors against humanity, human rights and human beings from happening again,” Hua said.

Suga also argued that it is inappropriate to apply for the UNESCO status when historians are sharply divided over estimated numbers of noncombatant victims in the Nanking Massacre that started in late 1937. China often claims about 300,000 Chinese were slaughtered by Imperial Japanese Army soldiers, while mainstream Japanese historians’ estimates of the victims vary from 40,000 to 200,000.

China and South Korea have been working closely to pressure Prime Minister Shinzo Abe to recognize Japan’s historical responsibility for World War II. The two countries increased their efforts following Abe’s controversial visit last December to Yasukuni Shrine, which honors Japanese leaders convicted of war crimes alongside millions of war dead.

The leaders of China and South Korea have refused to hold talks with Abe since he took office in December 2012, citing his nationalistic interpretation of history. Seoul and Beijing both insist that Japan has never fully accepted responsibility for the comfort women system or atrocities such as the Nanking Massacre.

In late May, China unveiled a stone monument on the outskirts of the ancient city of Xian to honor Koreans who fought to free their peninsula from Japanese colonial rule, which lasted from 1910 to 1945. The monument was built at the request of South Korean President Park Geun-hye, who proposed the idea during a state visit to China about a year ago.

South Korea said Tuesday it is considering making a similar application to UNESCO on the historical documents.

“As far as I know, there is an opinion within the government to seek the listing and the issue is being considered,” Foreign Ministry spokesman Noh Kwang-il said at a press briefing in Seoul. He said the South Korean government “is aware of the Chinese move.”

Information from Kyodo added