China declared victory on Friday over an encounter with a US surveillance aircraft overflying the contested South China Sea, saying its military "drove away" the intruder with radio warnings.

Beijing is in the throes of a rapid land-reclamation programme in the area, building artificial islands and facilities including an airstrip -- raising tensions with Washington and the risk of a standoff on the high seas.

China regards almost the whole of the South China Sea as its own and the foreign ministry condemned the overflight as "highly irresponsible and dangerous", warning that such actions could cause "unwanted incidents".

The US Navy has released video footage taken from the P-8 Poseidon surveillance plane, which received several warnings from the Chinese military to retreat as it flew over the South China Sea -- home to vital shipping lanes.

The footage showed a flotilla of vessels carrying out reclamation works in one lagoon, and an airstrip under construction on another island.

A CNN crew on board captured a tense radio exchange between the US aircraft and Chinese forces.

"This is the Chinese navy... This is the Chinese navy... Please go away... to avoid misunderstanding," a voice can be heard telling the Americans.

The Chinese navy issued eight such warnings during the P-8's flight near Fiery Cross Reef, one of the sites of Beijing's land reclamation effort, CNN reported.

American pilots replied in each case that they were flying through "international airspace".

Foreign ministry spokesman Hong Lei told a regular briefing in Beijing: "China garrison troops drove it away by radio in accordance with relevant regulations.

"US actions have posed threats to the security of Chinese maritime features, it is highly likely to cause unwanted incidents, it's highly irresponsible and dangerous. We are strongly dissatisfied with this."

He urged the US not to take "any risky and provocative actions", saying China would "take proper and necessary measures to guard against any harm to China's maritime features and incidents in waters and airspace," he added.

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China's state broadcaster, CCTV, played part of the CNN footage showing the Chinese navy ordering the US plane out of the area with Chinese subtitles.

The US does not recognise China's claims to the artificial islands.

But China has repeatedly said it has "indisputable sovereignty over the Nansha islands and adjacent waters", using its name for the archipelago known as the Spratlys.