China on Friday responded to Japan's repeated protest of its scientific exploration in Okinotori waters, saying that the two sides have different opinions over the nature of the waters in question.
Zhang cited the United Nations Convention on the Law of the Sea (UNCLS) to explain China's stance.
According to Article 121 of the UNCLS, an island is a naturally formed area of land, surrounded by water, which is above water at high tide. Rocks which cannot sustain human habitation or economic life of their own shall have no exclusive economic zone or continental shelf, Zhang said.
"The two sentences are written in the UN convention and they form a complete concept," she said.
She said China and Japan have different understandings to the nature and scope of the surrounded waters of Okinotori. "The two sides should properly handle the relevant issues through friendly consultation."
The Japanese government on Wednesday said a Chinese survey vessel was found carrying out research in its exclusive economic zone near Okinotori, an uninhabited reef 1,740 km south of Tokyo.
In response, Zhang told reporters Wednesday the Chinese vessel was carrying out normal scientific exploration on the high seas. She also urged Japan to stay clam and deal with the issue with prudence.