BEIJING - A Chinese mainland spokesperson on Monday said both sides of the Taiwan Straits should jointly safeguard national sovereignty and territorial integrity, as they both belong to one and the same China.

Zhu Fenglian, spokesperson for the Taiwan Affairs Office of the State Council, made the remarks in response to a new bill passed by Japan's Ishigaki municipal assembly.

Zhu reiterated that the Diaoyu Island and its affiliated islets have been an inherent part of China's territory since ancient times, and China has indisputable sovereignty over the islands.