Beijing on Friday strongly denounced Manila's attempt to build a permanent structure on Ren'ai Reef, and vowed a firm response to any provocations.

Reports said the Philippines plans to build a structure "like a shelter for fishermen" at Ren'ai Reef, while also mentioning suggestions of building a lighthouse or marine research center.

The reported plan constitutes "a major move" by the Philippines to once again disrupt the status of Ren'ai Reef and seriously violate China's sovereignty, Foreign Ministry spokeswoman Mao Ning said.

Ren'ai Reef is part of China's Nansha Islands, and China has indisputable sovereignty over the islands and their adjacent waters, Mao said.

"This was established in the long course of history, and is consistent with the international law, including the Charter of the United Nations," she said.

Mao dismissed the Philippines' claims that Ren'ai Reef falls in its exclusive economic zone and continental shelf.

The claims are based on the illegal, null-and-void South China Sea arbitral award made in 2016, and are untenable in law, she said.

According to the Declaration on the Conduct of Parties in the South China Sea signed by China and the Association of Southeast Asian Nations members, all parties should maintain the status of Ren'ai Reef, which is uninhabited and facility-free, the spokeswoman said.

Tensions in the South China Sea have risen since Philippine vessels intruded into Ren'ai Reef's adjacent waters earlier this month.

"Over the issue of Ren'ai Reef, the Philippines has repeatedly gone against its commitment, changed its policies, violated China's sovereignty and provoked China. This has led to a complicated situation," Mao said.

"China will take resolute measures against any violation of our sovereignty ... and firmly safeguard our territorial sovereignty and maritime rights and interests," she said.