By Alex Kirby
BBC News Online environment correspondent
The world's surviving elephants face a dangerous upsurge in poaching if ivory stockpiles are sold, conservationists believe.
African elephants: Increasingly rare
They say three southern African countries should be prevented from selling their confiscated tusks.
They insist safeguards planned to ensure the sales do not fuel the demand for ivory will not work.
They believe the sales could drive elephants to extinction in some countries within 20 years.
In November 2002, the United Nations Convention on International Trade in Endangered Species (Cites) agreed in principle to allow the sales.
The demand came from South Africa, Botswana and Namibia, who want to sell 60 tonnes of ivory amassed over the years, much of it seized from poachers.
The standing committee of Cites is meeting in the Swiss city of Geneva to set the detailed conditions on which the sales can go ahead.
The International Fund for Animal Welfare (Ifaw) says: "Poachers go into action when there is talk of Cites-approved legal sales, which they can use as a 'smokescreen'.
Dearth of information
"It is almost impossible to tell the difference between legal and illegal smuggled tusks or ivory pieces once on the market."
Orphans of the ivory poachers
Cites has agreed the stockpiled ivory can be sold only if rigorous rules are in place, and if there is enough information to prove the sales will not lead to an increase in the illegal killing of elephants.
Ifaw says a report it is sending to Cites delegates at the Geneva meeting "shows that these criteria simply cannot be met".
The report says a Cites programme called Mike (Monitoring Illegal Killing of Elephants) is still at an embryonic stage.
Mike is designed to measure any poaching impact of ivory trade decisions in the Asian and African countries with elephant populations.
But Ifaw says Mike will be unable to provide reliable data before 2008 at the earliest.
It says: "Without accurate baseline data on elephant populations, it is impossible to say what effect the potential sale could have on them."
Ivory sale should buy protection for the survivors
Ifaw says no ivory exporting or importing countries have adequate Cites-approved legislation or controls on the ivory trade.
It also believes the profits to be made from selling the stockpiles will be too small to help the elephants.
Cites says the profits, estimated to reach $5m, must be spent only on elephant conservation.
But Ifaw says it thinks the cost of tackling the increased poaching it believes is certain to follow the sales would dwarf any profits they realised.
It wants governments or international groups to buy the ivory and withdraw it from the market, so countries could benefit from the income while safeguarding their elephants.
There were about 1.3 million elephants in Africa in 1980, but within a decade the poachers had reduced the number to roughly 600,000, prompting Cites to ban the ivory trade in 1989.
Ifaw says there are only 300,000-450,000 African elephants today. No more than 35,000-50,000 Asian elephants are thought to survive in the wild.