The shipment flown on an Emirates flight was declared at Thai customs as mobile phone parts to take advantage of Thailand's agreement with Laos not to check cargo in transit. Thailand is a transit point for ivory forwarded to other markets such as China.
"Normally, this would have gone right through but we got the tip-off,” said Seree Thaijongrak, director of the investigation and suppression bureau for Thai customs.
Customs officials searched a transit cargo warehouse at the airport on Wednesday evening and found a consignment of 239 elephant tusks from South Africa
About 38,000 African elephants are killed each year for their tusks out of a total estimated population of half a million.
Since 1898, the Convention on International Trade in Endangered Species (CITES) has banned the international ivory trade. It does however allow for domestic sales.
Thailand, which is home to the Asian elephant, has its own ivory for use by local craftspeople. However, the latter is indistinguishable from African ivory. This has made Thailand a transit point for ivory forwarded to other markets such as China or South-East Asia.
China remains one of the largest importers of ivory. In 2008, the United Nations allowed China to trade with Botswana, Namibia, South Africa and e Zimbabwe in order to counter the illegal ivory trade.