China firmly opposes any action of the Philippines that harms China's sovereignty and rights and interests, Chinese foreign ministry spokesperson Guo Jiakun said on Tuesday.

Guo made the remarks at a regular press briefing in response to a query related to a so-called updated "maritime chart" by the Philippine National Maritime Council, which includes islands and reefs in China's Nansha Qundao such as Zhongye Dao and Mahuan Dao.

"Zhongye Dao and Mahuan Dao are part of China's Nansha Qundao and Chinese territory. China has indisputable sovereignty over Nansha Qundao and its adjacent waters," Guo said.

Noting that the scope of Philippine territory is defined by several international treaties, Guo said that China's Nanhai Zhudao, including Nansha Qundao, lie beyond that scope.

The Philippines has illegally occupied several islands and reefs in Nansha Qundao, claimed the so-called "Kalayaan Island Group" beyond its own territory and issued a so-called "maritime chart," which includes relevant islands and reefs of China's Nansha Qundao, Guo said.

"Those actions seriously violate China's territorial sovereignty and the UN Charter and relevant international laws, and are illegal, null and void," he said.

"China firmly opposes any action of the Philippines that harms China's sovereignty and rights and interests. China will continue taking necessary measures to firmly defend its territorial sovereignty and maritime rights and interests in the South China Sea," the spokesperson said.