TRAFFIC, which runs the ETIS database of illegal ivory trades, said there had been at least 13 large-scale seizures in 2011, totalling at least 23 tonnes of ivory -- representing about 2,500 elephants.
This compares to just six large seizures in 2010, weighing a total of just under 10 tonnes, and confirms a sharp rise in the trade evident since 2007.
"In 23 years of compiling ivory seizure data for ETIS, this is the worst year ever for large ivory seizures -- 2011 has truly been a horrible year for elephants," said Tom Milliken, TRAFFIC's elephant expert.
The watchdog warned that once the details of hundreds of smaller ivory seizures were collated, "2011 could well prove to be the worst year ever for elephants" since the ETIS database was set up in 1989.
Most illegal shipments of African elephant ivory end up in either China, where it is ground up and used in traditional medicine, or in Thailand, the watchdog said, with Malaysia the most frequent transit country.
Milliken said the increasing quantities of ivory being traded, many of them from either Kenyan or Tanzanian ports, reflected a rising demand in Asia as well as the increased sophistication of the criminal gangs who sell it.
They constantly change their routes to Asia to avoid detection, including switching from air to sea freight, and once the ivory products arrive, their documentation is amended to conceal the fact that they came from Africa.
"As most large-scale ivory seizures fail to result in any arrests, I fear the criminals are winning," Milliken said.
International trade in elephant ivory was banned in 1990, and ETIS (the Elephant Trade Information System) holds the details of more than 17,000 reported ivory and other elephant product seizures across the world since then. (AFP)