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Beijing has strongly criticised the sailing of a US navy warship close to its man-made islands in the South China Sea, saying the move posed a "threat to China's sovereignty".

Foreign ministry spokesman Lu Kang said on Tuesday that the USS Lassen, a guided missile destroyer, entered the waters near the islands "illegally" and "without receiving permission from the Chinese government".

The patrol by the USS Lassen was the most significant US challenge yet to a 22-nautical-kilometre zone China asserts around the Spratly archipelago, a disputed group of hundreds of reefs, islets, atolls and islands in the South China.

One US defence official said the US warship sailed within 22 nautical kilometres of Subi Reef. A second defence official said the mission, which lasted a few hours, also included a sail-by at Mischief Reef and would be the first in a series of freedom-of-navigation exercises aimed at testing China's territorial claims, Reuters news agency reported.

In an angry response, officials in Beijing said that "China will resolutely respond to any country's deliberate provocations.

"We will continue to closely monitor the relevant seas and airspace, and take all necessary steps in accordance with the need," the Chinese foreign ministry said in a statement, without giving any details on precisely where the US ship sailed.

"China strongly urges the US side to conscientiously handle China's serious representations, immediately correct its mistake and not take any dangerous or provocative acts that threaten China's sovereignty and security interests," the statement continued.

Strategic waterway

Beijing insists it has sovereign rights to nearly all of the South China Sea, even waters close to the coasts of other states.

The sea is a strategically vital waterway with shipping lanes through which about a third of all the world's traded oil passes, and the dispute has raised fears of clashes.


Interactive: Islands row around China


The second US defence official told Reuters that more patrols would follow in the coming weeks and could also be conducted around features that Vietnam and the Philippines have built up in the Spratlys.

"This is something that will be a regular occurrence, not a one-off event," said the official. "It's not something that's unique to China."

White House spokesman Josh Earnest referred questions on any specific operations to the Pentagon but said the US had made clear to China the importance of free flow of commerce in the South China Sea.

Washington has repeatedly said it does not recognise Chinese claims to territorial waters around the artificial islands.

"We operate routinely in the South China Sea and we'll sail in international waters at a time of our choosing," an official told AFP news agency.

'Strong message'

The decision to go ahead with the patrol follows months of deliberation and risks upsetting the already strained US-China ties.

"By using a guided-missile destroyer, rather than smaller vessels ... they are sending a strong message," Ian Storey, a South China Sea expert at Singapore's Institute of South East Asian Studies, told Reuters.

"They have also said, significantly, that there will be more patrols - so it really now is up to China how it will respond."

Brunei, Malaysia, the Philippines and Vietnam - members of the Association of Southeast Asian Nations - also claim parts of the sea. Taiwan is a sixth claimant.

Source: Agencies