BEIJING - Chinese patrol boats confronted Japanese vessels early yesterday in disputed waters in the East China Sea, the latest in a series of such encounters following Tokyo's nationalisation of islands in the area last month.

Four marine surveillance vessels entered the waters near the islands claimed by China and Japan at 10am local time, according to a statement from China's State Oceanic Administration.

The ships conducted surveillance on Japanese Coast Guard vessels in the area, "sternly expressed" China's sovereignty claim over the islands, and "carried out expulsion measures", the administration said.

Japanese Coast Guard spokesman Yuji Kito said ships from both countries flashed signs saying they were in their own territorial waters and demanding the other side leave.

"They have done this before and so have we," he said.

He added that the situation was not more intense than previous encounters.

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

Meanwhile, a biennial joint exercise by the Japanese and US military in Japan is scheduled for Nov 5 to Nov 16, a drill likely to anger China amid tensions over the islands.

About 37,400 military personnel from Japan will join 10,000 US troops in the exercise, said Japan's Self-Defence Forces.

AGENCE FRANCE-PRESSE, REUTERS