China on Friday said it is necessary to send marine surveillance planes in airspace over the Diaoyu Islands in order to safeguard its sovereignty.

Foreign Ministry spokesman Hong Lei made the remarks while commenting on Japan's representation over China's marine surveillance plane flying over the Diaoyu Islands on Thursday.

"The Diaoyu Island and its affiliated islets, including the sovereignty of the waters and airspace over the region, belong to China," Hong said.

He noted Japan had deployed ships and planes to illegally enter the waters and airspace over the Diaoyu Islands since September, to which China firmly opposed.

China had lodged representations to Japan to demand it stop the illegal activities in the waters and airspace over the Diaoyu Islands, but the Japanese did not respond to the request, he said.

Hong reiterated China's opposition to Japan's illegal "purchase" of the Diaoyu Islands, asking Japan to take steps with sincerity to solve relevant issues through talks, and drive bilateral ties back on a normal track.