China firmly rejects a new Philippine "maritime chart" covering islands and reefs in China's Nansha Qundao, Chinese Foreign Ministry spokesperson Guo Jiakun said on Tuesday, calling Manila's move illegal, null and void and harms China's sovereignty.

At a regular press briefing on Tuesday, the spokesperson was asked to comment on reports that the Philippine National Maritime Council on September 25 unveiled an updated "maritime chart," 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. China's Nanhai Zhudao, including Nansha Qundao, lie beyond that scope.

Guo said the Philippines' illegal occupation of several islands and reefs in Nansha Qundao, the designation of so-called "Kalayaan Island Group" beyond its own territory, and the so-called "maritime chart," which includes relevant islands and reefs of China's Nansha Qundao, seriously violate China's territorial sovereignty and the UN Charter and relevant international laws. Those actions are illegal, null and void.

Guo's remarks are China's latest response to the Philippines' illegal occupation and political manipulation in the South China Sea. 

The chart forms part of Manila's efforts to advance its territorial claims and consolidate its illegal occupation of islands and reefs in the South China Sea, Yang Xiao, a research fellow at the Institute for Peace and Development of the Chinese Academy of Social Sciences, told the Global Times on Tuesday.

By further entrenching its presence on features such as Zhongye Dao, the Philippines hopes to turn its occupation into a fait accompli, Yang said.

The move, together with Manila's earlier submission of a chart of Huangyan Dao to the United Nations, is part of a broader campaign of political maneuvering in the South China Sea, he said. The aim is to place these materials in international public records so they can be used to support Philippine positions in future diplomatic and legal disputes.

Manila is systematically compiling documentation for individual islands and reefs, translating positions set out in the illegal South China Sea arbitration and its Maritime Zones Act into technical documents, including charts and baseline coordinates, that can be cited in international forums, Yang said.

These moves serve domestic political purposes, he added. Taking a tough stance on China has become a form of "political correctness" in the Philippines, Yang said, pointing to Philippine Defense Secretary Gilberto Teodoro Jr.'s repeated provocative statements as an example.

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, Guo concluded.