"We are at a critical time in history for elephants. We are right on the edge of seeing a legalization of the trade in ivory," Saba Douglas-Hamilton of Save the Elephants campaign group told a news conference.

CITES finally banned all trade in ivory in 1990 after a long and emotional campaign spurred by a halving of the African elephant population through intense poaching.

There has been pressure ever since for the ban to be lifted.

"The CITES-permitted sales...could stimulate poaching. It would be better to wait for more information," said Dan Stiles, co-author of three reports on the ivory trade.

"Prices of ivory crashed after the ban on trade, but they are now rising again, reflecting rising demand," he added.

The latest report, published on Wednesday by Save the Elephants, identified China as the principal culprit in the rising illegal trade in poached African elephant tusks.

"China gets more smuggled raw ivory from Africa than any other country in the world," said Stiles, who spent a month in the country researching his sections of the report.

The vast bulk of the ivory is carved in small workshops scattered around China and re-exported via Hong Kong and Macao, although there is a rising domestic market too as the Chinese economy expands.

The majority of the exported ivory finds its way west to Europe and the United States - often hidden in consignments of legal mammoth ivory or artificially aged to evade the ban.

Mammoth ivory, now starting to come onto the market in large quantities as global warming thaws the permafrost in Canada and Russia and exposes the corpses of the long-dead woolly giants, is virtually indistinguishable from elephant ivory.

However, unlike elephant ivory, mammoth tusks smell and are harder to work but are not covered by the CITES ban.

Although there are occasional seizures of illegal ivory - with a massive 1.9 tons taken just earlier this month in Hong Kong - activists believe it is just the tip of the iceberg.

To make matters worse, poachers in Africa have taken to wiping out whole herds of elephants at a time to make it easier to collect the tusks, Stiles said, noting that 50 tons of ivory represented up to 10,000 slaughtered elephants.