Japan is protesting against the latest protracted incursion of Chinese coast guard vessels into its claimed territorial waters around the Senkaku Islands.

Japan’s coast guard said the Chinese vessels entered the East China Sea early last Tuesday and remained close to a Japanese fishing craft before leaving the area on Thursday evening.

One of the Chinese vessels came within two miles (3.2 kilometres) of the Tokyo-administered Senkaku Islands that, while also being claimed by China and Taiwan, lie within Japan’s 12-mile maritime limit.

Beijing refers to the strategically important uninhabited islands as the Diaoyu Islands.

Japan’s coast guard sent its own patrol ships to the area and demanded the Chinese vessels immediately leave Japan’s territorial waters, CNN quoted the coast guard as saying.

In response to a request for comment on the Japanese coast guard’s statement, China’s Foreign Ministry said the “Diaoyu Islands are part of Chinese territory” and accused Japanese fishing boats of making “repeated intrusions” into the area.

“This has seriously violated China’s sovereignty. Chinese coast guard ships launching on-site law enforcement activities against the right-wing Japanese fishing boats is a justifiable act protecting our sovereignty. Japan has no right to make groundless remarks, let alone to interfere and obstruct,” CNN reported.

The latest instance comes amid growing tension between the two East Asian neighbours, especially as China looks warily at Japan’s relationship with the US.

Last month, Tokyo hosted a summit for the increasingly active Quad security grouping of Japan, the US, Australia and India.

Meanwhile, senior officials from China and Japan are expected to soon hold a fresh round of talks regarding Beijing’s potential plans for exploration in a contested area of the East China Sea.

The Japanese government recently said there had been new construction that it suspects is related to gas exploration ventures in an area to the west of a Tokyo-proposed median line between the nations’ exclusive economic zones.

In 2006, Japan and China agreed to jointly explore for — and potentially develop — natural gas in the East China Sea’s Chunxiao trough.

However, after more than 10 rounds of talks, negotiations were suspended a couple of years later when political friction increased after a Chinese trawler collided with a Japan coast guard vessel.

Tokyo is said to also be concerned regarding a Chinese research vessel that was recently suspected of performing a survey in Japan’s EEZ, Kyodo News reported.

The Quad summit hosted by Japan in May saw the launch of a satellite-based maritime security initiative aimed at pursuing a free and open Indo-Pacific.

“The benefit of this maritime initiative will allow tracking of dark shipping and other tactical-level activities, such as rendezvous at sea; as well as improve partners’ ability to respond to climate and humanitarian events…,” the White House said in a media statement on the sidelines of the summit.