[BEIJING] China is building an airstrip on reclaimed land in a disputed part of the South China Sea, recent satellite pictures show, potentially raising tensions with several Southeast Asian neighbours.
Fiery Cross was little more than a reef when China began to turn it into an island in late 2014.
Now, satellite images taken last week and shown on the website of the Washington-based Centre for Strategic and International Studies (CSIS) show the runway - estimated at 3,110 metres in total - more than one-third complete, it says.
When in operation, it says, it will be able to "accommodate almost any type of aircraft that China would want to land".
Less than four weeks earlier, CSIS said two sections of 468 metres and 200 metres were under construction.
"Before this construction, China lacked the refuelling and resupply capabilities to reach the southern part of the South China Sea," it added.
"While they have not yet been built, Fiery Cross should be big enough to accommodate hangar facilities for Chinese aircraft." On Wednesday, defence journal IHS Jane's reported that pictures taken by Airbus Defence and Space on March 23 showed a section more than 500 metres long and 50 metres wide.
China claims nearly all of the South China Sea according to lines on maps published in the 1940s - locking it into disputes with several Southeast Asian neighbours.
Its island-building in the Spratlys, also claimed in whole or part by the Philippines and Vietnam among others, has been seen as part of an attempt to assert its territorial claims.
Philippine President Benigno Aquino told AFP on Tuesday that China's recent moves in the region should spark fear around the world, with military conflict possible.
Beijing quickly dismissed his comments as "groundless," adding that China's construction "does not impact or target any other countries".
Last November, the US warned that the Fiery Cross project could accommodate an airstrip.
"We urge China to stop its land reclamation program, and engage in diplomatic initiatives to encourage all sides to restrain themselves in these sorts of activities," military spokesman Lieutenant Colonel Jeffrey Pool said.
Vietnam, the Philippines and Malaysia have asserted their own claims by stationing troops in the Spratlys and building airstrips there from the 1970s onwards.
US President Barack Obama warned last week that Beijing should not "elbow aside" countries it is in dispute with in the South China Sea.