Chinese President Xi Jinping has told a Coast Guard command to strengthen its law enforcement capabilities in the East China Sea.

Observers say Xi's orders could prompt the Coast Guard to step up activities near the Senkaku Islands. Japan controls the islands. China and Taiwan claim them.

China's state-run television reported on Friday that Xi inspected the command office two days earlier and was briefed about its operations.

Xi reportedly pointed out the need to resolutely protect China's territorial sovereignty and maritime interests, and crack down on illegal activities.

Chinese Coast Guard ships have repeatedly entered Japanese territorial waters off the Senkaku Islands. The Japanese government has also urged China to remove a buoy placed within Japan's exclusive economic zone near the islands.

Prime Minister Kishida Fumio expressed deep concern over the situation in the East China Sea when he met Xi in the United States in November.

The Japanese government maintains that the Senkaku Islands are an inherent part of Japan's territory, in terms of history and international law. It says there is no issue of sovereignty to be resolved over them.