Hawks spokesperson Captain Paul Ramaloko said it was not clear how the rhino horns disappeared as there were no burglaries at the Assen police station.
The horns, one of two sets held at the police station since November, were confiscated after rhino poachers dehorned eight rhinos at the Klipkopspruit private reserve near Sun City, in North West.
Hawks spokesperson Captain Paul Ramaloko said on Tuesday a theft docket was opened.
"It is not clear how the horns disappeared because there were no burglaries at the station."
The only people with access to the storeroom were police officers who had the key, he said.
Klipkopspruit's owner Miles Lappeman told Beeld he learned of the disappearance of the horns on Friday.
According to the newspaper, he received a letter from the department of environmental affairs two weeks ago asking him to remove the horns from the police station, asking for an address where they could be stored.
Lappeman said he was not prepared to fetch the horns as by supplying his address he would render himself and his family a crime target.
Deadly year for rhinos
​A total of 102 rhino have been killed since the beginning of 2013, says the department of environmental affairs.
Spokesperson Albi Modise said on Wednesday that the Kruger National Park was the hardest hit, with four rhino being killed there this week alone.
A total of 70 Kruger National Park rhino have been killed since January 1. "In the past 48 hours five alleged poachers were arrested in Limpopo and one at the Kruger National Park. This means a total of 40 alleged poachers, among them three alleged couriers, have been arrested since the beginning of the year," said Modise.
Police officers recovered ammunition, rifles and a silencer from the suspected poachers. A total of 11 rhino have been poached in the North West, 10 in KwaZulu-Natal, seven in Limpopo and four in Mpumalanga. Modise said while the numbers remained high, there was a slight drop in the number of rhino killed per week.
"[It] may be attributed to the implementation of the turnaround strategy aimed at eliminating poaching by the South African National Parks," he said.
Last year, the country recorded that three rhino were being poached per week. This year, the number dropped to two. Over 630 rhino were killed by poachers in 2012. – Sapa