(photo by CGTN)

China’s oceanographic research vessel KAN407 was allegedly obstructed by Japan on Tuesday during a field trip near the Diaoyu Islands in the East China Sea.

The Japanese coastguard said the Chinese vessel, KAN407, was spotted dropping what looked like a cable into the sea.

The coast guard warned the Chinese vessel away, claiming it did not have permission to be in the area.

KAN407 was previously warned out of the area by Japanese authorities during a similar excursion on June 13.

A similar incident happened on July 2, when several Japanese media outlets reported a Chinese naval vessel’s alleged “invasion” of the Tsugaru Strait between Honshu and Hokkaido in northern Japan which connects the Sea of Japan with the Pacific Ocean.

Yin Zhuo, a rear admiral in the Chinese People's Liberation Army Navy, told CGTN that the incident was not an "invasion", but that the Chinese vessel passed through the strait in accordance with the law and did not pose any threat to Japan.

According to the United Nations Convention on the Law of the Sea, Tsugaru Strait is an international waterway where foreign ships, including naval vessels, can go through.