Japan Coast Guard officials say they spotted four Chinese government ships navigating just outside Japanese territorial waters around the Senkaku Islands in the East China Sea on Thursday morning.

The officials are staying on alert and continuing their monitoring activity so that the Chinese ships will not enter Japan's territorial waters.

This brings the total number of days this year that Chinese government vessels have been spotted in the contiguous zone near the islands to 334 -- the highest ever since the Japanese government purchased some of the Senkakus from a private Japanese owner in 2012. The previous annual record high of 333 was set in 2020.

Japan controls the Senkaku Islands. The Japanese government maintains the islands are an inherent part of Japan's territory. China and Taiwan claim them.

Chinese government vessels entered Japan's territorial waters around the Senkakus on 28 occasions this year. The annual figures have been hovering at around the same level in recent years.

Chinese government ships navigated for 72 hours and 45 minutes from December 22 through 25 in Japanese territorial waters off the islands, marking the longest-ever continued intrusion of its kind since the 2012 purchase.

Japan Coast Guard officials say they will work closely with relevant agencies and respond calmly and firmly to protect Japan's territory and waters.