The 511 elephant tusks, worth €5.5m and bound for Laos, were seized upon arrival on Saturday at a major port in Chonburi province in eastern Thailand.
The bust came after customs officials received a tip-off in Laos and Thailand and tracked the containers from Kenya, customs department director general Somchai Sujjapongse told reporters.
The ivory, hidden among tea leaves, was shipped out of Kenya on March 24 and went through ports in Sri Lanka, Malaysia, and Singapore before coming to Thailand, he said.
The bust came one week after Thai customs officials seized four tonnes of tusks that were smuggled from Congo and also destined for Laos in what they said was the nation’s biggest seizure.
Somchai said that the tusks seized last Saturday were “more beautiful and complete than the previous lot”, and that they would likely have been distributed to buyers in China, Vietnam, and Thailand had the shipment reached Laos.
Thailand is one of the top destinations for African ivory smuggling in Asia and could face international sanctions soon if it does not show progress in combatting the problem.
Poachers have killed tens of thousands of African elephants for their tusks in recent years to meet demand for ivory in Asia.
China has imposed a one-year ban on ivory imports amid criticism that its citizens’ huge appetite for ivory threatens the existence of Africa’s elephants.