A UN body rejected proposals by Zambia and Tanzania to reopen trade in ivory that experts say would have worsened a surge in illegal trafficking driven by Asian-based organised crime.
After a tense debate, the Convention on International Trade in Endangered Species, meeting in Doha, voted down Tanzania's request to sell 80.5 tonnes of stockpiled ivory to Japan and China.
Zambia later withdrew its own bid for a one-off sale of 21.7 tonnes worth several million dollars.
Efforts by both countries to downlist wild populations of the intelligent mammals to a lower level of protection were also slapped down in separate votes.
"We are sitting on a treasure that we are not allowed to use to help our population, to help the poor build schools and roads," said Stanslaus Komba, from Tanzania's ministry of natural resources.
The move to reopen ivory trade - banned since 1989 with the exception of a few one-time sales - comes on the heels of a dramatic surge in illegal trafficking since 2005.
"Large-scale ivory seizures are becoming not only more frequent but larger in size," said Tom Milliken, head of the Elephant Trade Information System.
Organised crime syndicates in Asia have also gotten into the act to satisfy growing demand in the region, he said.
In Africa, the countries most directly involved in the traffic have been Nigeria and the Democratic Republic of Congo, while in Asia activity was particularly high in Thailand, he added.
Some 25 tonnes of the precious material - culled from an estimated 2,600 elephants - were confiscated last year, mainly in Asia, according to wildlife trade monitoring group Traffic.
All told, tens of thousands of elephants are likely butchered every year for their tusks, experts say. Poachers have taken to using heavy arms to carry out military-style operations, leaving local law enforcement outmatched.
"They fire on herds with rocket launchers," said Cosma Wilungula Balongelwa, a delegate from the Democratic Republic of Congo, citing cases from earlier this year.
Except for populations in four southern African nations, African elephants in two dozen other range states are listed on CITES Appendix I, which bans cross-border trade.
Tanzania and Zambia sought a downlisting to the less restrictive Appendix II, which allows commerce if it is monitored and deemed sustainable.