Two of eleven Chinese patrol craft cruising the waters off two disputed islands between China and Japan have entered what Tokyo claims as its territorial waters, the Japanese navy said on Tuesday.
The Japanese navy told NHK national TV the appearance of 11 Chinese vessels so close to its shores was unprecedented.
The islands, known as the Senkaku to Japan and Diaoyu to China, have been at the center of a dispute recently that has triggered violent anti-Japanese protests across China and caused Japanese companies to suspend operations in China.
The issue flared up after Japan nationalized three of the five islands last week, which previously belonged to a private owner.
Beijing and Tokyo cannot agree on a maritime border in the economic zones around the islands. Japan claims it has occupied the islands since 1895, while Beijing says Japanese charts dating back to 1783 show the islands as Chinese territory.
The islands were controlled by the United States after World War II and granted to Japan in 1972. Both Taiwan, to which the pre-1949 Chinese government moved, and Beijing, maintain Japanese occupation of the islands is illegal.