On a quiet hillside lying in the eastern fringes of China's famed porcelain capital of Jingdezhen, a team of potters sweat in a secret kiln, moulding wet kaolin clay into knockoffs of antique Ming and Qing wares.

"This bowl I would give 85 points out of 100," said the boss of the guarded kiln complex, holding up a reproduction Qing dynasty bowl and placing it beside a near-identical prototype - a broken original pieced together from 280-year-old blue and white shards from the reign of the Yongzheng emperor.

A Qing enamelled "swallows" bowl sold for nearly $19 million in 2006, making it the most costly Asian artwork ever auctioned.

"The auction houses and buyers often can't tell the difference," he added, running his finger over the smooth glaze and telltale blue Yongzheng reign mark on the base of the bowl - the finest copy of a now discarded batch of lesser fakes which could fetch over $100,000 (Dh367,000) in the open market, he said.

The jet-setting Jingdezhen ceramics trader who spoke on condition of anonymity is a small link in an increasingly global chain of top fakers, dealers and collectors who've extended the reach of the secretive multi-million-dollar fake ceramics trade in recent years, riding the crest of China's art market boom.

"A large number of fakes are finding their way into auctions everywhere," said Anthony Lin, a former chairman of Christie's in Asia who now runs his own Oriental art dealership.

Since the Yuan dynasty (1279-1368 AD), some of the finest porcelain ever created has come from the imperial kilns at Jingdezhen in southern China, including translucent monochrome celadons, rare Ming Chenghua wares as well as the exquisitely coloured and decorated Qing enamel "famille-rose" ceramics.

Even in the Qing period (1644-1911), potters were making knockoffs, so-called "houmenzao" or back-door copies of Ming masterpieces.

Authentication problem

Teams of potters in elite kilns, sometimes backed by foreign dealers with the know-how and distribution networks to plant fakes overseas in old family estates or country auctions, have upped the deceit to a new level over the past decade.

"It has spoilt the whole industry, because people have no confidence," said Kaiyin Lo, an eclectic Hong Kong collector of Chinese art including ancient jades, calligraphy and ceramics.

Adding to the risk is the difficulty of authentication. While scientific authentication including thermoluminescence testing to date the wares is available, fakers have devised methods using old clay and "radiating" their wares to age them artificially.

"I think the game has been the same for the past few decades, but the knowledge needs to be updated ... it's always been a challenge and we'll have to continue to keep those fakes from Jingdezhen in check, it'll continue to be an area where we have to be increasingly vigilant," said Nicolas Chow, head of Chinese ceramics and artwork at Sotheby's Hong Kong.