BEIJING, Oct. 20 (Xinhua) -- The Southern Theater Command of the Chinese People's Liberation Army on Sunday expelled an Australian P-8A military aircraft that illegally intruded into China's territorial airspace over the Xisha Qundao, a Chinese military spokesperson said on Monday.

Li Jianjian, spokesperson for the Air Force of the theater command, said that the P-8A had illegally intruded into China's territorial airspace over the Xisha Qundao without the approval of the Chinese government.

The theater command had organized naval and air forces to conduct tracking and surveillance, take strong countermeasures, and issue warnings to drive the Australian aircraft away in accordance with the relevant laws and regulations, Li said.

The spokesperson emphasized that Australia's actions had seriously violated China's sovereignty and posed a high risk of triggering maritime and air incidents.

"We sternly warn Australia to immediately cease its infringements and provocative acts," Li stressed. "The theater command's troops remain on high alert at all times and will resolutely safeguard national sovereignty and security, and regional peace and stability."