Poaching of the animals jumped by 43 percent between 2011 and 2012 and so far this year one rhino had been killed by poachers every 11 hours, said the International Union for Conservation of Nature (IUCN), based In Gland in the canton of Vaud.
Last year at least 745 rhinos were poached across Africa, with 668 of the animals killed in South Africa alone, it said in a statement.
And since 2006 nearly 2,400 rhinos have been killed across Africa, slowing the population growth to its lowest levels since 1995, it said.
"Well-organized and well-funded crime syndicates are continuing to feed the growing black market with rhino horn," said Mike Knight, who heads the IUCN's
African Rhino Specialist Group.
"Over the past few years, consumers' use of rhino horn has shifted from traditional Asian medicine practices to new uses, such as to convey status," he explained, pointing out that demand in Vietnam was especially escalating.
There are currently 5,055 Black Rhinoceros and 20,405 White Rhinoceros in Africa, according to the organization.
While the populations are continuing to grow slightly, they will begin declining in less than two years if the poaching continues to increase, IUCN said.
The organization called on the international community, and especially the main rhino horn markets Vietnam and China, as well as transit hub Mozambique, "to urgently address the crisis by strengthening and enforcing regional and international trade laws, particularly in relation to rhino horn."
The plight of rhinos and African elephants, which are increasingly being poached for their ivory, will be among the top issues discussed at a summit on endangered species in Bangkok next month, organized by UN wildlife trade regulator CITES.