Hong Kong's seized ivory stockpile an elephant-sized headache

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.