Authorities have killed two suspected poachers, arrested two others and found 11 rhino carcasses in the same area of South Africa's Kruger National Park in one week, a spokesman said Thursday.

"Our rangers were conducting a routine anti-poaching operation on Wednesday night when they came across suspected poachers," said park spokesman Reynold Thakuli. "A gunfight ensued and two of them were shot dead.

He said the others managed to flee, and that they were suspected to have escaped across the border to Mozambique.

Anther two poachers were arrested on Thursday, he said. Three more dead rhinos were also found, just two days after the discovery of eight carcasses in the same area.

Kruger, one of South Africa's top tourist destinations, has been hit hard by poachers, with 252 rhinos killed there in 2011 -- more than half the estimated 450 killed last year across South Africa. The 2010 figure was 333.

The country has beefed up security inside the park, with soldiers deployed to assist rangers.

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

"The men carried hunting rifles, axes and other weapons," said Thakuli.

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.