An illicit cache of elephant tusks, rhino horns and leopard skins with an estimated value of $5.2 million was seized Tuesday in Hong Kong by customs officials, marking the second big bust of illegal endangered species imports in a month in the busy port city.

Officials found 1,200 polished ivory tusks, 13 black and white rhino horns and five leopard skins, according to the South China Morning Post. The ivory was reportedly worth more than $1,000 per kilogram, the rhino horns more than $25,000 per kilogram and the leopard skins could fetch tens of thousands of dollars each on the illegal blackmarket.

The shipment was seized in Hong Kong after being routed from Nigeria to Shanghai, where it was transferred to another ship. But Hong Kong customs officials believe the final destination of the cargo was mainland China.

The contraband was stored in two wooden crates inside two separate shipping containers.

"Hong Kong is a very busy shipping port and smugglers might think there is a good chance of smuggling in contraband," Vincent Wong Sui-hang, group head of customs port control, told the Post. "But we have the capability and are determined to smash the smuggling rings."

However, Wong cited the logistic difficulties of searching through every bit of cargo at the world's third busiest port, which is likely why so many smuggled items flow through it.

"We do not have the capacity to check every [container]," Wong said to the Post. "If we process each and every container, we won't be ranked the No 3 port in the world."

As of Thursday, no arrests were made in connection with the illegal goods.

Less than three weeks ago, 1,148 elephant tusks -- more than 2 tons of ivory -- worth an estimated $2.2 million was found in a container originating from the West African nation of Togo by Hong Kong customs officials. The bust was Hong Kong's biggest ivory seizure since 2010, according to a report by Associated Press.

Investigators are looking into who was behind the shipments and trying to determine if they were in any way connected.

"Forensic evidence could confirm the likelihood that the two products originate from very different regions of Africa and implies a high degree of organization and sophistication in their operations," Richard Thomas, a spokesman for Traffic, a wildlife trade monitoring network, told the Post.

Under Hong Kong law, anyone found guilty of smuggling or trading products from endangered species could face up to two years in prison and up to a $645,000 fine, according to the AP.