Rangers in South Africa's Kruger national park, already struggling to cope with well-armed rhino poachers, said Tuesday they were preparing to face a new onslaught against the park's elephants.

More than one thousand rhino were slaughtered in South Africa last year, mostly in Kruger, but the park had been spared elephant poaching for more than a decade -- until May.

Then, a bull elephant was found shot dead with its tusks hacked off -- an ominous sign that the poaching ravaging populations to the north and east had made its way over the border.

"We are ready. We have the resources to tackle this head on," said Markus Hofmeyer, head of veterinary services at South African National Parks, which manages Kruger.

"The fight against rhino poaching has equipped us with the necessary skills."

But those skills and resources are already strained, with more than 500 rhino killed in the first six months of this year and increasingly sophisticated poachers using semi-automatic rifles.

Rhino poaching jumped from 13 animals being killed in 2007 to the slaughter of 1,004 last year -- mostly in the park, which is roughly the size of Wales and shares a border with Mozambique.

The WWF last month raised the alarm over plummeting elephant populations in Mozambique after an aerial survey showed ivory poaching was decimating herds in the country.

Elephant poaching is also rife further north in Kenya, Tanzania and Zimbabwe.

Rhino horn and elephant tusks are sold on a lucrative black market, mostly in Asia.

But elephant poaching should not reach the same crisis level as that of rhino, as ivory sells for much less than rhino horn, said Hofmeyer.

"The killing of elephants would require much bigger weapons and the animal generally makes a lot of noise, attracting attention," he said.

The Kruger park has around 16,200 elephants, according to 2012 figures.

Despite increased policing -- including army patrols along the border -- rhino killings have risen steadily every year.

Last year the Kruger acquired a military aircraft equipped with sophisticated surveillance technology to detect poachers.