Malaysian authorities have seized nearly 700 elephant tusks bound for China, an official said, the latest in a series of hauls indicating Malaysia had become a key ivory transit hub.

Inspectors discovered the 695 African elephant tusks, worth three million ringgit ($1 million), on Friday in Klang, Malaysia's biggest port, customs official Zainul Abidin Taib told AFP on Tuesday.

They were in two containers labeled "recycled plastic" that had arrived from Tanzania's largest city of Dar es Salaam, he said.

He added that as-yet unidentified criminal syndicates were behind a series of recent attempts to smuggle tusks through Malaysia and authorities were struggling to keep up with increasingly sophisticated traffickers.

"It is our social responsibility to end this ivory trade. The world at large has branded Malaysia as a hub (for elephant tusks)," said Zainul, the national customs bureau's assistant director general for enforcement.

Wildlife watchdog TRAFFIC has said the global illegal ivory trade has grown since 2004, largely due to expanding demand in increasingly prosperous China, where ivory is often ground up and used in traditional medicines.

Hong Kong authorities last month seized nearly two tonnes of elephant ivory worth about $1.7 million in a shipment that had transited through Malaysia.

Malaysian authorities also have seized more than 1,000 African elephant tusks in two separate shipments in the past two months, the New Straits Times newspaper reported on Saturday.

TRAFFIC's Southeast Asia Regional Director William Schaedla in a statement the latest Malaysian ivory seizure was "both heartening and disappointing."

"It's heartening because it shows that the country's authorities can and will take action on the problem," he said.

"It's disappointing because it clearly validates what TRAFFIC has been saying for some time now -- Malaysia is a major transshipping country for illegal ivory."

"Illegal wildlife trade is fluid. Now that the ivory traffickers have been caught out using some of Malaysia’s ports, they are likely to move through others in an effort to keep their black market business alive," Schaedla said.