Black market rhino horn sells for up to USD 60,000 (57,000 euros) per kilo -- more than gold or cocaine -- with most demand from China and Vietnam where it is coveted as a traditional medicine and aphrodisiac.

In the last eight years alone, roughly a quarter of the world population has been killed in South Africa, home to 80 percent of the remaining animals.

"These criminal gangs are armed to the teeth, well-funded and part of transnational syndicates who will stop at nothing," the ministry said in a statement.

"This decrease can be attributed to the efforts of our men and women on the ground, especially our rangers."

During 2016, South African police arrested 680 people for rhino-related poaching compared to 317 in 2015.

Most were caught in and around the celebrated Kruger National Park -- a major tourist attraction.

A total of 148 firearms were also seized inside the park in 2016.

Jo Shaw, the World Wildlife Fund's South Africa rhino programme manager, said that more needed to be done to break up the gangs.

"Unless we see the transnational crime syndicates targeted the problem won't go away. We know Vietnam was identified at CITES as not yet doing enough," Shaw told AFP, referring to a recent gathering of countries signed up to a key treaty on endangered species.

"While it's reassuring to see that the decline seems to be continuing, there's a long way to go. We need a long term approach to the challenge," she said.

In 2007 just 13 rhinos were killed for their horns in South Africa before reaching a peak of 1,215 in 2014, according to the TRAFFIC wildlife trade monitoring group.

Rhino horn is composed mainly of keratin, the same substance as in human nails.