China on Friday expressed strong displeasure at the Japanese leader's remark on Diaoyu Islands, with Foreign Ministry spokesman Hong Lei saying that it "sabotages China's territorial sovereignty."

On the same day, Japanese Prime Minister Yoshihiko Noda told the press that Japan claimed Diaoyu Islands were part of its territory. The Meiji government integrated them into Japan in 1895 without the signs of rule by the Qing Dynasty of China at that time.

Hong stressed that the Diaoyu Islands and surrounding islets "have been the inherent territory of China since ancient times" because they "were first found, named and used by the Chinese."

The earliest historical record of Diaoyu Islands can be dated back to China's Ming Dynasty (1368-1644) in a book titled "Departure Along the Wind" (published in 1403), in which the names of "Diaoyu Islet" and "Chiwei Islet" were used. The names refer to the nowadays Diaoyu Islands and Chiwei Islet, Hong said.

He went on to say that Hu Zongxian, the Zhejiang governor of Ming Dynasty, marked Diaoyu Islands and surrounding islets in China's maritime defense.

"It demonstrated that these islands were at least within China's maritime defense sphere since the Ming Dynasty," Hong said.

Japan claimed its sovereign requirement during the China-Japanese War in 1895 and seized the islands with illegal means. "The saying that Diaoyu Islands were inherent territory of Japan is totally groundless," Hong said.

The Cairo Deceleration issued after the World War II regulated that all territory illegally taken by Japan, including China's northeast, Taiwan and Penghu islets, must be returned to China, according to the spokesman.

In August 1945, Japan announced its unconditional surrender under the terms of Potsdam Proclamation. "It means Japan must return Taiwan, the Diaoyu Islands and surrounding islets to China," he said.

On Sept. 18, 1951, then Chinese Premier and Foreign Minister Zhou Enlai made a solemn statement on behalf of the Chinese government that the Treaty of Peace with Japan signed in San Francisco of the United States was illegal and invalid, and it absolutely would not be recognized without the preparation and signing of the People's Republic of China.

In June 1971, Japan and the United States signed a pact to hand over Okinawa to Japan. Diaoyu Islands were mapped in the handover area.

"It is a private trading of the Chinese territory," Hong said.

China's Foreign Ministry announced on Dec. 30 of 1971 that such a move was "totally illegal" and reiterated that Diaoyu Islands and surrounding islets were "an integral part of the Chinese territory", he said.