South Africa announced Sunday it was beefing up the number of rangers in the world-renowned Kruger national park after an alarming jump in the number of rhinos slain by poachers for their horns.

"This ongoing poaching of our rhino population is a source of great concern for the government... It requires of us all as a collective to take drastic measures to help combat it," said Environment Minister Edna Molewa.

Kruger, one of South Africa's top tourist destinations, has been plagued by poachers, with 252 rhinos killed there in 2011 -- more than half the estimated record 448 slaughtered last year across South Africa. The 2010 figure was 333.

The fate of the critically endangered black rhino species is particularly worrying. Nineteen were felled last year, including eight in Kruger.

The dramatic spike in rhino killings has been driven by demand for its use in Asian traditional medicine, especially in China and Vietnam, where it is believed to cure cancer despite scientific evidence to the contrary.

Poachers are using high-powered weapons and veterinary tranquilisers to dart rhinos before hacking off their horns.

"The government of South Africa views the illegal killing of this national treasure in a very serious light and will continue to prioritise our fight against this crime jointly with our law enforcement agencies," Molewa said.

She told a press conference in the capital Pretoria that the government would be boosting the number of rangers in Kruger by 150 from 500 currently to try to address the poaching onslaught.

A 150-kilometre (95-mile) electric barrier will also be installed along the border between the Kruger and neighbouring Mozambique, where many of the poachers are recruited.

Since April 2011, South African soldiers have been patrolling the Mozambique border but the move appeared to have done little to deter poachers.

In the last two years, at least one rhino is killed on average every day by heavily armed poachers, some who carry kalashnikovs or use helicopters or bribe rangers to help spot the rare animals.

"The police are very under-resourced," Pelham Jones, who heads the association of private rhino owners, told AFP.

"For every rhino poached, there are three or four guys to be arrested, we are talking about thousands and the number of the police are very small," he added. Last year, police arrested 232 people, up from 165 in 2010.

Some 7,000 reserves in South Africa are privately owned, including 400 in which rhinos can be found.

Jones' association is calling for trade in rhino horn to be legalised, as part of an effort to combat illegal commerce.

A feasibility study into the viability of legalising such trade within South Africa -- currently the subject of a national moratorium -- is due to be concluded by August this year.

South Africa is home to about 20,000 rhinos, or between 70 and 80 percent of the global population of the giant mammal.