The Japan Coast Guard says Chinese government vessels intruded into Japanese territorial waters near the Senkaku Islands in the East China Sea and stayed there for 80 hours and 36 minutes.

That represents the longest intrusion into the waters by such ships since the Japanese government purchased some of the islands from a private Japanese owner in 2012. The previous record was 72 hours and 45 minutes registered from December 22 to 25 last year.

The coast guard says four Chinese government vessels started entering the waters near the islands of Minamikojima and Uotsurijima shortly after 11 a.m. on Thursday. They appeared to be following three Japanese fishing boats.

The coast guard says one of the Chinese vessels left the area on Saturday night after one of the fishing boats had done so. It adds that the other Chinese vessels also sailed out of there by 7:44 p.m. on Sunday.

The coast guard remains on the alert and is warning the Chinese vessels not to enter the waters again.

Japan controls the Senkaku Islands. China and Taiwan claim them. The Japanese government maintains the islands are an inherent part of Japan's territory, in terms of history and international law. It says there is no issue of sovereignty to be resolved over them.