WASHINGTON — China has reclaimed more land in the disputed Spratly islands of the South China Sea than previously known, according to a Pentagon report released yesterday, which says Beijing is also completing the construction of a runway on one of its seven man-made outposts.

Since China’s land reclamation efforts began in December 2013, it has reclaimed more than 1,170ha of land as of June this year, the report said. American officials had previously put the total at 809ha as of May.

Once the airstrip on Fiery Cross Reef is operational, China could use it as an alternative runway for carrier-based planes, allowing the Chinese military to conduct “sustained operations” with aircraft carriers in the area, the report said.

China’s sole aircraft carrier, a Soviet-era ship bought from Ukraine and refitted in China, has carried out exercises in the South China Sea but is not yet fully operational. Some experts believe China will deploy domestically built carriers by 2020 as part of plans to develop an ocean-going “blue water” navy.

At the reclamation sites in the Spratlys where China is in the building phase, it has excavated deep channels and constructed new berthing areas to allow access for larger ships, said the report, called the Asia-Pacific Maritime Security Strategy. “The infrastructure China appears to be building would enable it to establish a more robust power projection presence into the South China Sea,” it added.

In a statement, the Chinese Foreign Ministry said China had “completed the relevant island and reef area reclamation project” at the end of June. Construction activities were “completely within the scope of China’s sovereignty”, it added.

Early this month, United States Secretary of State John Kerry told a meeting of regional leaders in South-east Asia that China’s construction of facilities on man-made islands for “military purposes” was raising tension and risked “militarisation” by other claimant countries.

Mr Kerry also criticised “restrictions” put in place in recent months by China, saying Washington would not accept any restrictions on freedom of navigation and overflight.

This drew a sharp response from Beijing. Freedom of overflight and navigation does not mean allowing foreign warships and military jets to violate other countries’ sovereignty and security, the Chinese Foreign Ministry had said in a statement

Chinese Foreign Minister Wang Yi announced earlier this month that Beijing had halted all land reclamation. China says the outposts will have undefined military purposes, as well as help with maritime search and rescue, disaster relief and navigation. But there is concern within the region that these efforts will hamper freedom of navigation.

China claims most of the South China Sea, through which US$5 trillion (S$7 trillion) in ship-borne trade passes every year. The Philippines, Vietnam, Malaysia, Taiwan and Brunei also have overlapping claims.

The reclamation campaign significantly outweighed efforts by other claimants in size, pace and nature, said the Pentagon report.

China had reclaimed 17 times more land in 20 months than the other claimants combined over the past 40 years, accounting for approximately 95 per cent of all reclaimed land in the Spratlys, it added.

“China is unilaterally altering the physical status quo in the region, thereby complicating diplomatic initiatives that could lower tensions,” said the report. AGENCIES