The last year has seen a major increase in the illegal ivory trade, with more involvement from organised crime.

去年象牙非法交易量显著增长，多数是有组织的犯罪。

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The number of seizures has gone up, and so has their average size

Figures compiled（编译） by Traffic, the agency charged with monitoring the trade, show a doubling in the volume of illegal ivory seized from 2008 to 2009.

Researchers believe most of it is poached in West and Central Africa, while China is the main destination.

Traffic says there is no evidence that last year's one-off legal sale of ivory in southern Africa boosted smuggling³（走私）.

The volume of ivory seized is not a complete indication of the size of the illegal trade, because the effectiveness of police and customs authorities can vary from year to year and only a fraction（分数，小部分） of illegal consignments⁵（交付，委托） are discovered.

Nevertheless, Traffic believes a significant increase lies behind the seizure¹ figures, especially because the final numbers for 2009 could rise even higher.

"Our analysis cuts off in August, and our figures are already showing the increase," said the agency's director Steven Broad.

"So it's a serious concern. And the increase is based on a relatively⁶ small number of big seizures, which tend to indicate more organised operations behind the trade," he told BBC News.

A year ago, an operation by Interpol and Kenyan authorities netted a tonne of ivory in a single consignment⁴ - the biggest on record - and led to the arrest of 57 people in five African countries.

Reports indicate that prices of $1,000 per kilo can now be commanded.

China question

Traffic believes that poaching and exporting is currently concentrated in West Africa.

Nigeria emerges as a country implicated⁷ in many seizures made elsewhere, but whose authorities have not themselves made a single seizure in 18 years.

As sources of ivory, Traffic also picks out Cameroon and the Democratic Republic of Congo as countries of concern, while Thailand stands accused as a major trans-shipment point.

More than half of the consignments involving these countries are large ones, indicating the involvement of organised crime, Traffic says.

Tanzania emerges as a nation effective at controlling poaching in its own elephant herd⁸, but which gangs are increasingly using to export ivory.

Traffic concludes that most of the illegal ivory ends up in China, although Vietnam is developing as a market.