BEIJING (BLOOMBERG) - China's armed forces accused the United States of "ill intentions" in the South China Sea after an American warship entered waters near the contested Spratly Islands last week.

"The US ship's deliberate provocation during the traditional lunar Chinese New Year festival, which harboured ill intentions, is a naked act of navigational hegemony," Senior Colonel Li Huamin, spokesman for the People's Liberation Army's southern command, said in a statement on Tuesday (Jan 28).

"China has indisputable sovereignty over the South China Sea and its islands, and no matter how the US deliberately schemes, comes up with new tricks, provokes and stirs up trouble, its efforts will be fruitless."

The USS Montgomery, an Independence-class combat ship, was tracked by PLA forces last Saturday sailing in an area adjacent to where China controls a man-made island, without Beijing's authorisation.

China, Vietnam, Taiwan, Malaysia, Brunei and the Philippines each claim sovereignty over some or all of the Spratly Islands.

Lieutenant Joe Keiley, spokesman for the US Navy's Seventh Fleet, said in an e-mail on Wednesday that no ship - civilian or military - required permission before engaging in "innocent passage" through territorial seas and that the manoeuvre was consistent with international law. He said the USS Montgomery was sent to challenge such restrictions imposed by China, Vietnam, and Taiwan.

"This freedom of navigation operation upheld the rights, freedoms and lawful uses of the sea," Lt Keiley said.

The US has increased patrols in the South China Sea since the Pentagon officially labelled China a "strategic competitor" in 2018 as the world's two biggest economies battle for influence in the Asia-Pacific.