It's the latest in a string of illegal ivory shipments uncovered by Hong Kong authorities over the past few years.
Wildlife activists say China's growing presence in Africa has led to a huge surge in poaching of elephants for their tusks, most of which are believed to be smuggled into China and Thailand to make ivory ornaments.
Wong said the smugglers changed their methods after three other big shipments from Africa were confiscated in Hong Kong this year.
"The smugglers tried a different modus operandi," Wong said. "Instead of one shipment they packed the bulk into three shipments for different consignees. They used different vessels on different voyages to try to evade customs inspections."
In August, Hong Kong officials seized illegal ivory, rhino horns and leopard skins worth $5.3 million in a shipment that came from Nigeria. In late July, they found two tons of tusks worth $2.25 million in a container from Togo. In January, a shipment of ivory worth $1.4 million from Kenya was confiscated.