So far this year 146 animals have been killed for their horns, they said, a rate that could end up with a total surpassing the 668 animals killed last year.
Delegates to the Convention on International Trade in Endangered Species conference in Bangkok were told rising demand for the horns, believed by Asians to have medicinal properties, is behind the slaughter, the BBC reported Friday.
Edna Molewa, South African minister for water and environmental affairs, said unless action is taken by 2016 the number of rhinos killed each year would outnumber births.
"The indication is that if we do more of the same, the same work every day, more of the same will not help us produce a better result," she told the Bangkok conference.
"By 2016, we will begin to run into trouble, the graph will begin to slide down -- we shall be losing more on a continuous basis."