An international wildlife trade group says more elephant tusks were seized in 2011 than in any year since 1989, when the ivory trade was banned.
Traffic said 23 tonnes of ivory were seized - representing at least 2500 dead animals.
Trade in ivory was banned in 1989 to save elephants from extinction.
But Traffic says it has continued illegally because of huge demand in Asia, where it is used to make decorative objects.
A statement from Traffic said most illegal shipments of African elephant ivory end up in either China or Thailand.
The group said there were at least 13 large seizures of ivory this year, amounting to more than 23 tonnes, compared to six last year of less than 10 tonnes.
"2011 has truly been a horrible year for elephants," elephant expert Tom Milliken said.
Malaysia was a transit country in six of the seizures in 2011.
In the most recent case on 21 December, African elephant tusks worth about $US1.3 million were seized in Mombasa.
Traffic said the ivory was hidden in containers of handicrafts being shipped to Cambodia from Kenya.
Despite all the seizures, Mr Milliken said there were generally few arrests.