CHINA threatened “serious consequences” today after the United States Navy undermined “the peace and stability of the South China Sea” by sailing a destroyer in disputed waters for the second day in a row.

Beijing insisted that the move was a violation of its sovereignty and security.

The warning comes as the US ramps up the tensions in the region and its military continues to enter into Chinese territorial waters. 

On Thursday the USS Milius guided-missile destroyer sailed near to the Paracel Islands, with China saying it had to mobilise its navy and air force to drive it off.

The US denies the claim that the vessel were forced out of the territory by the Chinese. 

But on Friday, the US again sailed the ship in the vicinity of the islands, which are claimed by China, the rump Republic of China government on Taiwan and Vietnam.

The US Navy said that it was conducting a “freedom of navigation operation” to challenge requirements from all three nations requiring either advance notification or permission before a military vessel sails by.

US 7th Fleet spokesman Lieutenant Luka Bakic said in a  statement: “Unlawful and sweeping maritime claims in the South China Sea pose a serious threat to the freedom of the seas, including the freedoms of navigation and overflight, free trade and unimpeded commerce and freedom of economic opportunity for South China Sea littoral nations.”

He said: “The US challenges excessive maritime claims around the world regardless of the identity of the claimant,” Lt Bakic said.

China’s Ministry of National Defence responded by accusing the US of “undermining the peace and stability of the South China Sea.

“The act of the US military seriously violated China’s sovereignty and security, severely breached international laws, and is more ironclad evidence of the US pursuing navigation hegemony and militarising the South China Sea,” ministry spokesman Tan Kefei said. 

“We solemnly request that the US immediately stop such actions of provocation, otherwise it will bear the serious consequences of unexpected incidents caused by this.”

He said China would take “all necessary measures” to ensure its security, but did not elaborate.

China repeated again that it had driven the US ship away from the islands.