Hong Kong is fast becoming the Fort Knox of ivory.

As one of the chief gateways to mainland China -- the world's largest market for ivory, according to animal welfare groups -- Hong Kong has seized tons of what Chinese collectors call "white gold."

In the last six months alone, more than six tons of elephant ivory worth close to $HK50 million ($US6.5 million) was confiscated in Hong Kong. In one shipment alone, Hong Kong authorities seized 3.8 tons of tusks, equivalent to one-sixth of the total illegal ivory confiscated worldwide last year.

Where this ivory is stored in Hong Kong is a closely guarded secret.

"For security reasons, we are not in a position to disclose further details of the keeping premises and the seized items," a spokesman for Hong Kong's Agriculture, Fisheries and Conservation Department told CNN.

With a black market price of almost $3,000 a kilogram, Hong Kong's authorities are taking no chances.

"The keeping premises are equipped with adequate security measures such as security guards and CCTV surveillance," he said.

But high-profile thefts in Zambia and Botswana have highlighted the security headache and the drain on resources that ivory stockpiles pose for countries.

"For many countries where ivory is detected entering the country illegally and seizures take place, especially involving large amounts of ivory, there is the very real possibility, given its current high value and the expense involved with maintaining security, of it finding its way onto the market," said Dr Naomi Doak, the Greater Mekong Program Coordinator for the wildlife trade monitoring network TRAFFIC.

"A number of countries have come out and acknowledged that they have lost ivory from stockpiles," she added.

Part of the problem, she said, was that countries are only required by international agreements on animal trade to report the weight rather than the number of tusks confiscated.

"If (countries) have to provide detailed records including the number of pieces as well as the weight of individual items, it makes it easier to verify and also allows more information to be used in analysis such as transportation trends," she said.

Scientists have begun a program of mapping poaching hotspots by analyzing DNA from seized tusks. For Grace Ge Gabriel, regional director for the International Fund for Animal Welfare, stockpiles are an invaluable resource in creating a crime database.

"There is a lab that has been set up in the University of Washington in the U.S. where they have already constructed a map of African elephant DNA which will help them pinpoint which country the ivory came from and where the poaching hotspots are," she told CNN.

Gabriel said that more often than not, poaching is repeated in the same areas. Information of this type helps law enforcers to choke off the trade at source.

While the Hong Kong stockpile is among the best protected in the region, and authorities have been quick to cooperate with the DNA database program, Gabriel said stockpiles in general present a risk.

"We feel that confiscated ivory requires a lot of capacity to keep it in a secure location and leaving it in these places will always tempt people to get their hands on it."

According to the Convention on International Trade on Endangered Species (CITES) which wrapped up in Bangkok this week, a large amount of confiscated African ivory goes missing every year.

"The size of ivory stockpiles in many countries in and outside Africa, and their possible contribution to the illegal ivory supply chain, remains another important gap in the current understanding of the dynamics of the illegal ivory trade," a report unveiled at CITES -- entitled "Elephants in the Dust, The African Elephant Crisis" -- stated.

"This gap could be substantially narrowed through mandatory, regular inventorying," it said. "Forensic techniques may help to establish the extent to which ivory in illegal trade is derived from poaching or was leaked from official stockpiles."