China warns of reprisal as Japanese city changes disputed area name

The row over the uninhabited East China Sea islets may add to recent tension caused by Japan's criticisms of Beijing's plan to impose a new national security law in Hong Kong.

China has said Japan should not interfere in Beijing's internal affairs.

The disputed islands are known as the Senkaku in Japan and the Diaoyu in China.

Japanese broadcaster NHK reported earlier that the Ishigaki City assembly in Okinawa, in southern Japan, had passed a bill to change the name of the administrative area covering the islands to Tonoshiro Senkaku from Tonoshiro, from Oct 1.

The bill was "a serious provocation to China's territorial sovereignty, is illegal, invalid, and cannot change the fact that the Diaoyu Islands belong to China", the Chinese foreign ministry said.

"China's resolve and determination to protect its territorial sovereignty is unwavering," ministry spokesman Zhao Lijian told reporters at a daily briefing.

China has lodged a complaint with Japan and reserved the right to take further action, Zhao said.

NHK said the name had been changed to avoid administrative mistakes as another location in Ishigaki City was also called Tonoshiro.