TOKYO — China on Thursday sent a warship for the first time into disputed waters near a group of Japanese-controlled islands in the East China Sea, the Japanese government said.

Japanese officials said they had summoned the Chinese ambassador in Tokyo around 2 a.m., after the warship, a frigate, was spotted less than 24 nautical miles from the uninhabited island chain, known as the Senkaku in Japan and the Diaoyu in China. The ship left after about two hours, officials said.

China regularly sends nonmilitary patrol vessels to the area, where they engage in cat-and-mouse chases with the Japanese Coast Guard. But it was the first time in the long and sometimes tense dispute over the islands and their surrounding waters that China had used a naval ship to so directly challenge Japan’s control, the officials said.

“China’s actions unilaterally escalate tensions in the area, and we are seriously concerned,’’ Yoshihide Suga, the Japanese chief Cabinet secretary, said at a news briefing. Prime Minister Shinzo Abe ordered the Japanese Navy and Coast Guard to be on alert, Suga added.

China’s Ministry of National Defense did not explicitly confirm that the ship had entered the disputed waters, but it defended its right to send vessels there.

“The Diaoyu Islands and affiliated islands are Chinese territory. For China’s military vessels to pass through waters under the country’s own jurisdiction is reasonable and legitimate, and other countries have no right to make irresponsible comments,’’ the ministry said in a statement.

New York Times