Two Chinese coast guard vessels entered Japan's territorial waters near the Senkakus on Tuesday, a day after a Chinese naval ship was spotted near the China-claimed islands, as tensions continue to heighten between Tokyo and Beijing despite the approaching 50th anniversary of the normalization of diplomatic ties.

The Japan Coast Guard said the intrusion, the 15th this year and the first since June 23, happened around 4:35 a.m., adding that its patrol vessels ordered the two Chinese ships to exit the waters immediately.

The coast guard said the pair of vessels entered the waters near the group of uninhabited islets, claimed by China, in the East China Sea after the vessels tracked a Japanese fishing boat.