ISTANBUL

Japan on Monday alleged four Chinese ships entered its territorial waters, navigating a few kilometers away from Japanese fishermen.

The ships entered territorial waters near the islands of Minamikojima and Uotsurijima around the disputed Senkaku Islands in the East China Sea, the Japanese Coast Guard said.

The islands are known as Diaoyu Islands in China.

It is the second time this year that Tokyo has alleged Chinese vessels trespassed into its territorial waters. The first incident was reported on Jan. 10.

According to Japanese public broadcaster NHK, the coast guard has “dispatched patrol vessels to ensure the safety of the Japanese ships and to warn the Chinese vessels to leave Japan's territorial waters immediately.”

Claimed by China and controlled by Tokyo, the disputed islands, Tokyo insists, “are an inherent part of Japan's territory, in terms of history and international law. There is no issue of sovereignty to be resolved over them.”