More than three tonnes of elephant ivory have been found at a Thai port stashed in a container shipped from Kenya, customs said Monday, the second huge haul of tusks from Africa in less than a week.

The discovery, which would be worth millions of dollars on the black market, was destined for Laos where the illegal ivory trade flourishes.

Some 511 pieces of ivory, weighing over three tonnes, was found on April 25 in a container "marked as tea leaves transported from Mombasa, Kenya, and on to Laos", Thai customs said in a statement.

Scores of whole tusks -- some nearly two metres long -- were among the pieces seized.

A record four tonnes of African elephant ivory was seized at Bangkok's main port on April 20, in a container that arrived from the Democratic Republic of Congo and was also destined for Laos.
Once in neighbouring Laos, authorities believe the ivory would likely be sold on to buyers from China, Vietnam or back into Thailand, countries where ivory ornaments are coveted despite fears the trade is pushing wild elephants to extinction.

Laos "is increasingly being used as a major transit point for such large volumes of illicit ivory and other wildlife products", Chris Shepherd of conservation group TRAFFIC told AFP.

"The increase in large-scale seizures is of great concern.  Whether the ivory is coming from freshly killed elephants, or from stockpiles of ivory in Africa, needs to be investigated," he added.

Conservationists say poaching and conflict has destroyed large numbers of African elephants in the wild, prompting experts to warn the species could be wiped out within decades.

Thailand has launched a crackdown on the ivory trade amid mounting international pressure.

Global regulator Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) has threatened an international ban on Thailand's entire wildlife business if it fails to curb the trade in tusks on its soil.

Under Thai law, registered ivory from domesticated Thai elephants can be sold. But experts say that loophole allows criminal gangs to launder poached African ivory through the kingdom.

Thailand's fishing industry is also under scrutiny for exploitation of migrant workers and over-fishing.

Last week the European Union threatened to ban Thai fish imports unless the kingdom does more to halt illegal fishing.

Thailand is the world's third largest seafood producer and an EU ban could cost it around $1 billion annually.