CITES, whose 171 member nations begin a two-week meeting in The Hague on Sunday, is credited with stemming the slaughter of the African elephant by banning the global ivory trade in 1989.

But scientists and environmentalists say the killing of elephants for their tusks, mainly in central Africa, has now reached levels not seen since 1989, as Asian-run organised crime gangs push the illegal ivory trade to unprecedented heights.

Last year alone, experts estimate as many as 23,000 African elephants were illegally killed.

Some environmentalists say that a CITES decision to allow a one-off sale of 50 tonnes of ivory from Botswana, Namibia and Zimbabwe in 1997 increased black market demand for ivory and put elephants in grave danger.

The convention allowed the 1997 exports on the ground that some southern African elephant populations had recovered and were well managed.

A second one-off sale was agreed in principle in 2002 but was made conditional on the compilation of up-to-date data on elephant poaching and population levels. The CITES Standing Committee agreed on Saturday that this had been done and the 60-tonne export of existing stocks to Japan could go ahead.

The debate on elephants is between the benefits that ivory sales may bring to conservation and local communities living side by side with large and sometimes dangerous animals, and concern that such sales may increase poaching, CITES said.

"The baseline data will make it possible to determine objectively what impact future ivory sales may have on elephant populations and poaching," it said in a statement.

The meeting in The Hague will see heated discussion as African countries are split between those wanting to protect the beloved elephant and those which say elephant populations have grown at an unsustainable rate.