Taiwan says a Chinese government ship has been sailing in its "prohibited" waters around the Kinmen Islands, which are close to the Chinese mainland.

Taiwan's Ocean Affairs Council chief Kuan Bi-ling said on Tuesday that a China marine surveillance vessel entered its "prohibited" waters the previous day. She also said four China coast guard ships sailed in "restricted" waters the same day without permission.

Chinese authorities are previously thought to have tacitly recognized the existence of the controlled areas.

Taiwan claims entering the "prohibited" zone is a de facto violation of its territorial waters.

On February 14, a Chinese fishing boat capsized near the Kinmen Islands while being chased by the Taiwanese coast guard. Two of the crew of four died.

China responded sharply to the incident and announced that it would step up patrols in the area.

Last week, an official Chinese vessel was confirmed to have navigated in the "prohibited" waters.

Kuan expressed anxiety about the Chinese authorities' intention, describing it as having a strong political significance and close to a declaration of sovereignty.

Chinese government ships have regularly entered Japan's territorial waters near the Senkaku Islands in Okinawa Prefecture. There is a view in Taiwan that Chinese authorities are taking a similar approach with the Kinmen Islands.

Japan controls the Senkaku Islands. China and Taiwan claim them.

The Japanese government maintains the islands are an inherent part of Japan's territory in terms of history and international law.