The United States does not have the right to get involved in problems between China and the Philippines, the Chinese foreign ministry said on Thursday, as tensions simmer over conflicts in disputed waters of the South China Sea.

"The U.S. is not party to the South China Sea issue, it has no right to get involved in a problem between China and the Philippines," said ministry spokesperson Mao Ning at a regular press briefing when asked about the U.S. saying it will defend the Philippines.

China and the Philippines have had several high-profile confrontations in the South China Sea, most notably in disputed waters around the Second Thomas Shoal, part of the Spratly Islands.

Last Sunday, a Chinese vessel collided with a Philippine boat, with Manila condemning "in the strongest degree" the "dangerous blocking manoeuvres" of the vessel.

"The U.S. promise of defending the Philippines must not hurt China's sovereignty and maritime interests in the South China Sea, and it also must not enable and encourage the illegal claims of the Philippines," Mao said.

A spokesperson for the Philippine foreign ministry did not immediately respond to a request for comment.

U.S. President Joe Biden said on Wednesday at the White House that America's commitment to Philippines defence remains "iron-clad," after accusing China of acting "dangerously and unlawfully" in the South China Sea.

"Any attack on the Filipino aircraft, vessels, or armed forces will invoke ... our Mutual Defence Treaty with the Philippines," Biden said in remarks during a joint meeting with Australia's prime minister.

The United States and the Philippines recently agreed on new guidelines for their 1951 Mutual Defence Treaty. The guidelines now specifically mention that mutual defence commitments would be invoked if there were an armed attack on either country “anywhere in the South China Sea”.