The Chinese military warned off a United States warship that illegally entered China's territorial waters off the Xisha Islands in the South China Sea on Saturday, a spokesman for the People's Liberation Army said.

Senior Colonel Tian Junli, spokesman for the PLA's Southern Theater Command, said on Saturday that the guided-missile destroyer USS Hopper illegally intruded into China's territorial waters off the Xisha Islands on Saturday without the approval of the Chinese government.

The theater command has organized air and naval forces to follow and monitor it, and drove it away according to law, he said.

Tian criticized the US action as a serious violation of China's sovereignty and security, and "another iron proof" that the US is pursuing "navigation hegemony" and creating "militarization of the South China Sea."

He said that it fully showed that the US is a "security risk maker in the South China Sea" and the "biggest destroyer" of peace and stability in the region.

The spokesman warned that the troops of the theater command will remain on high alert at all times and resolutely safeguard national sovereignty and security as well as the peace and stability in the South China Sea.