The Chinese government's determination to safeguard its sovereignty over the Diaoyu Islands is unswerving, Foreign Ministry spokesman Hong Lei said Wednesday.

Hong made the comment in response to media reports that the Japanese government has decided to buy the islets for 2.05 billion yen (26.15 million U.S. dollars) from the islands' Japanese private owners.

The Diaoyu Islands and its surrounding islets have been China's inherent territory since ancient times, Hong said.

"The islands were first found, named and used by the Chinese. They have been within China's maritime defense sphere since the Ming Dynasty (1368-1644)," Hong said.

Japan asserted its sovereignty during the China-Japanese War in 1895 and seized the islands through illegal means, Hong said.

Despite China's repeated representations, Japan has turned a blind eye to China's demands and deliberately continued the purchase process, which has undermined China's territorial sovereignty, Hong said.

He reiterated that any unilateral action by Japan regarding the Diaoyu Islands is illegal and invalid.

"China is closely following the development of the issue and will take necessary measures to protect its territorial sovereignty," Hong said.