Customs officials in Thailand say they've seized 4 tons of ivory worth $6 million hidden in bean sacks in what they're calling the biggest bust in the country's history.

Customs Department Director-General Somchai Sujjapongse says the 739 elephant tusks were bound for Laos but seized at a port in Bangkok.

He said Monday that the shipment, falsely labeled as beans, was shipped out of Congo in February, went through Malaysia and arrived at the Bangkok port on Saturday.

Thailand is one of the top destinations for African ivory smuggling in Asia and could face international sanctions soon if it doesn't show progress in combating the problem.

Somchai said authorities believe that had the ivory gone through to Laos, it would have been distributed to buyers in China, Vietnam and Thailand.