Poachers in South Africa killed more than 100 rhinos in the first three months of this year, most of them inside national parks — highlighting an ongoing battle to protect one of the best-known endangered species.

South African Environment Minister Dion George announced the figures on Monday and said that 65 of the 103 rhinos killed between Jan. 1 and March 31 were poached in national parks.

The average of more than one rhino killed a day is in line with last year's count and "a stark reminder of the relentless threat to our wildlife," George said.

South Africa has the largest rhino population in the world, with an estimated 16,000 to 18,000 animals, according to conservation groups. That includes black and white rhinos.

Black rhinos are only found in the wild in Africa and are listed as critically endangered, with around 6,400 left, according to the International Union for Conservation of Nature. Around 2,000 are in South Africa.

"In the last decade, poachers have killed almost 10,000 rhinos across Africa to feed the demand for horn on the black market," the IUCN says.

The organization says rhino horn is "a lucrative, illicit commodity sought after by well-established, organized and powerful transnational criminal syndicates." There is demand for horn in Asia, particularly in Vietnam and China, which continues to threaten all five species of rhino, it says.

South African authorities have focused in recent years on criminal syndicates they believe are behind much of the country's rhino poaching. The environment ministry hailed a conviction last year of what it called a poaching "kingpin" from Mozambique. Simon Ernesto Valoi was sentenced to 27 years in prison by a Mozambique court for running an operation poaching rhinos in South Africa's huge Kruger National Park, which borders Mozambique.

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