China's Ministry of Foreign Affairs said Thursday that it is "normal" for a Chinese marine surveillance plane to patrol the airspace over the Diaoyu Islands in the East China Sea, prompting Japan to scramble fighter jets to the area.

According to a statement on the website of the State Oceanic Administration (SOA), China's Haijian B-3837 aircraft reached the airspace over the Diaoyu Islands at 10 am Thursday, joining the flotilla of marine surveillance ships Haijian-50, Haijian-46, Haijian-66 and Haijian-137 to patrol the area.

The SOA said that during the patrol, the flotilla stated the Chinese government's position on the islets to the Japanese vessels, demanding they leave the area. On its website, it also posted two photos of the islands shot from the airplane.

The aircraft is a twin-engine propeller plane used for surveillance or monitoring of fishing activities.

The incident prompted Japan's military to scramble eight F-15 fighter jets, Japan's Defense Ministry said. Japanese officials later said the Chinese aircraft had left the area, Reuters reported.

The Japanese Defense Ministry said it was the first time that a Chinese plane had entered "Japanese airspace" since Japan started recording similar incidents in 1958, Kyodo News reported. Japan later protested to China over the incident.

China's foreign ministry spokesman Hong Lei told a regular press briefing Thursday that it's normal for China's marine surveillance planes to fly in the airspace over the Diaoyu Islands, as Diaoyu Island and its affiliated islets are China's inherent territory.

"China demands Japan stop its illegal activities in the waters and airspace of the Diaoyu Islands," Hong stated.

Han Zhiqiang, charge d'affaires at the Chinese embassy in Tokyo, said China hadn't accepted the Japanese side's diplomatic representation over the incident, the China News Service reported.

Liu Jiangyong, a vice dean of the Institute of Modern International Relations at Tsinghua University, told the Global Times that after the US handed Okinawa over to Japan in 1972, Tokyo brought the Diaoyu Islands into its Air Defense Identification Zone (ADIZ).

"Sending a plane to the area was a breakthrough in terms of challenging Japan's ADIZ, which was arbitrarily drawn up by Tokyo a long time ago," said Liu, noting that the struggle over the Diaoyu Islands would enter a new phase following China's success in carrying out routine patrols in the waters of the islets.

Liu also highlighted the increasing risk in terms of conflicts brought about by air confrontations.