Japan is threatening to cut funding for the United Nations' cultural body after it agreed to include documents related to the 1937 massacre carried out by Japanese colonial forces in the Chinese city of Nanjing.
Chief Cabinet Secretary Yoshihide Suga said Monday the decision by UNESCO to accept the documents from Beijing for its Memory of the World register was "problematic," considering Tokyo and Beijing have conflicting views of on the matter.
Suga said Japan was seeking "fairness and transparency" in the UNESCO program to prevent it from being used for political purposes. He said the government is reviewing its all of its support of UNESCO, including financial.
The foreign ministry says it donated about $31 million to UNESCO in 2014, or nearly 11 percent of Japan's total U.N. budget.
Tens of thousands of people were killed when Japanese troops invaded and occupied Nanjing, one of the world's worst atrocities of the World War Two era.
China puts the death toll at 300,000 people, but other scholars put the number much lower. Many of its Asian neighbors feel Japan has not sufficiently atoned for war crimes against its troops committed throughout the region in the first half of the 20th century, through the end of World War Two.
Among the documents submitted by China are files from two post-war tribunals established to investigate the massacre.
UNESCO's Memory of the World program was founded in 1992 to preserve and safeguard historical documents.