China defended its recent maritime law enforcement activities in waters near Ren'ai Reef and Huangyan Island on Wednesday, and decried the United States' endorsement of the Philippines' maritime provocation.

The US Department of State issued a statement related to the South China Sea on Sunday, attacking China's actions over the two maritime islets.

"For some time, in seeking selfish geopolitical interests, the US has incited, supported and cooperated with the Philippines in the latter's infringement and provocation at sea, and repeatedly sought to threaten China by citing the US-Philippines Mutual Defense Treaty," China's Foreign Ministry spokeswoman Mao Ning said at a regular news conference.

Such moves embolden the Philippines in violating China's sovereignty, violate the purposes and principles of the United Nations Charter and jeopardize regional peace and stability, Mao said.

The so-called South China Sea arbitral award made in 2016 is illegal, null and void, Mao reiterated.

Accusation unfounded

Any threat, coercion or unfounded accusation will not thwart China's resolve to protect its territory, sovereignty and maritime interests, she said.

China has said it has indisputable sovereignty over the islands in the South China Sea, including Ren'ai Reef and Huangyan Island, as well as their adjacent waters.

In another development, Mao slammed the United Kingdom on Wednesday for interfering in the affairs of Hong Kong, after UK Foreign Secretary David Cameron met with the son of Jimmy Lai.

The UK side was reported to have said that it opposes China's National Security Law and will continue to support Lai.

Lai instigated chaos in Hong Kong and colluded with foreign forces to undermine national security, and the Hong Kong Special Administrative Region government is beyond reproach for bringing him to justice, the spokeswoman said.

The UK is interfering in Lai's case, which has entered the judicial process, Mao said.

Also, the UK, which has just passed its own national security bill, is playing double standards by opposing China's National Security Law, the spokeswoman said.

More than 80 percent of Hong Kong residents believe the National Security Law has made Hong Kong safer, Mao said, urging the UK to stop interfering in the affairs of Hong Kong and China's internal affairs.