Rhinos' horns are big business for poachers in Africa and Asia
Rhino poaching around the world is set to reach a 15-year high, conservation groups have warned.
They say demand for the threatened animals' horns is being driven by the traditional medicine trade in Asia.
The groups estimated that the number of rhinos being killed in southern Africa had risen four-fold in recent years.
The findings were presented at a meeting of the Convention on International Trade in Endangered Species (Cites) in Geneva.
"Rhinos are in a desperate situation," said Heather Sohl, species policy officer for conservation group WWF.
"This is the worst rhino poaching we have seen in many years and it is critical for governments to stand up and take action."
The briefing, prepared by WWF, the International Union for the Conservation of Nature (IUCN) and Traffic, highlighted some of the threats facing the animals.
"Illegal rhino horn trade to destinations in Asia is driving the killing, with growing evidence of Vietnamese, Chinese and Thai nationals in the illegal procurement and transport of rhino horn out of Africa," it observed.
The document also said that rhino poaching was a problem in Asia itself, with evidence of about 10 of the animals being killed in India and a further seven being slaughtered in Nepal since January.
Conservationists fear that recent successes in stablising rhino populations over the past decade are being undone by the upsurge in poaching.
"Increasingly daring attempts by poachers and thieves to obtain the horn is proving to be too much for rhinos and some populations are seriously declining," warned Steven Broad, executive director of Traffic.
Under Cites, almost all rhino species fall within "Appendix I", which means that any international commercial trade in any rhino parts is outlawed.
The conservation groups said it was vital for the international community to get an "accurate and up-to-date picture on the status, conservation and trade in African and Asian rhinos".
Dr Jane Smart, director of the IUCN's Biodiversity Conservation Group, added: "IUCN and its African and Asian Rhino Specialist Groups are working hard to gather data and information on rhinos so that Cites parties can make informed decisions and ensure that rhinos are still here for generations to come."