Japan owes an explanation to China and the international community as to why it is unwilling to clearly state the commitments it has made in the past and its legal obligations, Foreign Ministry spokesman Lin Jian said on Thursday.

Lin made the remark at a daily news conference in Beijing, when asked about the comments Japanese Prime Minister Sanae Takaichi made on Wednesday in Japan's Upper House about the China-Japan Joint Statement of 1972.

As a landmark political document underpinning China-Japan ties, the statement's Article 3 states that "the Government of the People's Republic of China reiterates that Taiwan is an inalienable part of the territory of the People's Republic of China", and "the Government of Japan fully understands and respects this stand".

While some Japanese media outlets claimed that Takaichi specifically cited this stand on Wednesday, Lin clarified on Thursday and said the reports have been proved to be inaccurate as Beijing has verified what exactly Takaichi said.

Takaichi merely said that "the Japanese government's basic position regarding Taiwan remains as stated in the 1972 Sino-Japanese Joint Statement, and there has been no change to this position", and nothing more, Lin said.

Based on her remarks on Wednesday, Lin asked whether Takaichi "can accurately and fully articulate that position".

"Why is the Japanese side unwilling to clearly state the commitments it has made and its legal obligations? What is the logic and motive driving this attitude? The Japanese side owes China and the international community an explanation," he said.

Liu Jiangyong, a professor of Japanese studies at Tsinghua University, said the China-Japan Treaty of Peace and Friendship — signed by the two countries in 1978 and approved by their highest legislative bodies — is a legal document that recognizes the principles and contents of the 1972 statement, and the treaty makes it clear that the statement underpins peaceful, friendly bilateral relations.

"As Article 98 of Japan's Constitution says 'the treaties concluded by Japan and established laws of nations shall be faithfully observed', it is the obligation of the Japanese government and Japanese lawmakers to faithfully abide by the contents of the 1972 statement and 1978 treaty," he added.

On Nov 7, Takaichi made provocative comments at a parliamentary debate, talking of Tokyo's possible military intervention in Taiwan.

Lin, the spokesman, said that China's stance is very clear.

"We urge the Japanese side to reflect on and correct its wrongdoing, and retract Prime Minister Takaichi's erroneous remarks," Lin said. "This is an issue of principle. The facts and Japan's commitments are written down in black and white in historical records."

zhangyunbi@chinadaily.com.cn