TOKYO/TAIPEI >> A Chinese aircraft carrier entered Japan’s contiguous waters for the first time on Wednesday, Japan’s defense ministry said, the latest in a string of military maneuvers that have ratcheted up tensions between the neighbors.

The carrier, accompanied by two destroyers, sailed between Japan’s southern Yonaguni and Iriomote islands, entering an area that extends up to 24 nautical miles from its coastline where Japan can exert some controls as defined by the United Nations.

Japan’s Deputy Chief Cabinet Secretary Hiroshi Moriya said Tokyo had conveyed its “serious concerns” to Beijing, describing the incident as “utterly unacceptable from the perspective of the security environment of Japan and the region”.

“We will continue to closely monitor Chinese naval vessels’ activities in the waters around our country and will take all possible measures to gather information and conduct vigilance and surveillance,” Moriya told a news conference.

Japan last month lodged a protest with China after one of its naval survey vessels entered Japanese waters, shortly after an airspace breach. In July, a Japanese navy destroyer made a rare entry into China’s territorial waters near Taiwan, according to the Japanese media.

An uptick in Chinese military activity near Japan and around Taiwan in recent years has stoked concerns in Tokyo. Japan has responded with a defense buildup it says aims to deter China from using military force to push its territorial claims in the region.

Earlier on Wednesday, Taiwan’s defense ministry said it had spotted the same Chinese aircraft carrier group sailing through waters off its east coast in the direction of Yonaguni, Japan’s southernmost island, which is about 69 miles east of Taiwan.

China, which views democratically governed Taiwan as its territory, has been staging regular exercises around the island for five years to pressure it to accept Beijing’s claim of sovereignty, despite Taipei’s strong objections.

The ministry said the Chinese ships, led by Liaoning, the oldest of China’s three aircraft carriers, were spotted in the early hours of the morning on Wednesday sailing through waters to the northeast of Taiwan.

Taiwan tracked the ships and sent its forces to monitor, it said. China’s defence ministry did not answer calls seeking comment.