Beijing on Monday fired back at US criticism of an artificial island project in the disputed South China Sea that could reportedly include an airstrip, with a top general defending it as "justifiable".

People's Liberation Army Major General Luo Yuan told the state-run Global Times newspaper that Beijing was building infrastructure on the reef and the US should stay out of the issue.

"The US is obviously biased considering that the Philippines, Malaysia, Vietnam have already set up military facilities," Luo was quoted as saying.

"China is likely to withstand the international pressure and continue the construction, since it is completely legitimate and justifiable," he added.

A report last week by IHS Jane's Defence revealed new details of a vast land reclamation project China is undertaking on Fiery Cross Reef, known as Yongshu in China.

It is part of the Spratly Islands, which the Chinese call Nansha.

Beijing claims nearly all of the resource-rich South China Sea, while Brunei, Malaysia, the Philippines, Taiwan and Vietnam have their own claims, several of them also building structures on reefs or occupying islands.

According to the IHS Jane's Defence report the artificial island is a huge 3,000 metres (1,000 feet) long and 200-300 metres wide, one of several reclamation projects being pursued by China in the region but apparently the first that could accommodate an airstrip.

A harbour also has been dug out on the east side of the reef that appears large enough for tankers and naval warships, it said.

Days after the report, the US called on China to halt the project and for other governments to cease similar efforts.

"We urge China to stop its land reclamation programme, and engage in diplomatic initiatives to encourage all sides to restrain themselves in these sorts of activities," US military spokesman Lieutenant Colonel Jeffrey Pool said.

But the Global Times contended Monday that China was building on the reef "mainly to improve the living standards of the reef-stationed soldiers".

The US, which is "not a claimant" in the South China Sea, has been acting "selfishly" in the region, the paper added in an editorial.

"China's construction on the Yongshu Reef will not be affected by US words," the Global Times wrote.

It added: "The Yongshu Reef is becoming a big island, which shows China's prominent construction capabilities."