China has criticised the US Navy's decision to sail "without permission" close to an artificial island Beijing claims in the South China Sea, labelling the move "provocative", once again ratcheting up tensions in the disputed waterway.

The protest lodged by China's defence and foreign ministries on Thursday came after the US conducted its first freedom-of-navigation operation in the contentious area since Donald Trump took office in January. The USS Dewey sailed within 12 nautical miles of Mischief reef in the Spratly Islands, which is currently occupied by China but lies within the Philippines Exclusive Economic Zone (EEZ).China's defence ministry spokesman Ren Guoqiang criticised the US for "showing off its military strength," and said it would only "encourage militarisation of the area."

He said warnings were sent to the US ship to leave the area and an explanation had been sought from US officials.

China has labelled the US Navy's decision to sail "without permission" close to an artificial island Beijing claims in the South China Sea as provocative. AP

The South China Sea is subject to a web of territorial disputes involving China, the Philippines, Vietnam, Malaysia, Brunei and Taiwan and has been one of the region's major flashpoints. Beijing's aggressive moves to construct man-made islands on top of reefs and militarise its outposts has attracted heavy criticism and the US conducted a series of freedom-of-navigation operations under the Obama administration. Australia was under pressure to join these operations.

However, since Mr Trump came to power, Washington has been more focused on the Middle East and securing China's help to address North Korea's nuclear ambitions. The freedom-of-navigation operations appeared to be on hold.