China has reiterated that the Diaoyu Islands are part of China's territory and China has indisputable sovereignty over them.

Chinese Foreign Ministry spokesperson Hua Chunying was responding to a question about a protest from Japan, after Chinese coastguard ships and fishing boats sailed around the Diaoyu Islands.

The spokesperson urged Tokyo to remain calm. She also warned Japan against taking any action that could raise tensions in the area, or complicate the situation.