The mauled body of the student, identified in local media as Andrew Oberle, was retrieved from the enclosure by paramedics under armed guard at the Jane Goodall Institute Chimp Eden near the eastern town of Nelspruit.

"When we found him, he was in a foetal position underneath a lapa with massive injuries, lacerations, abrasions, partial amputation from his head to toe," said Lloyd Krause, spokesman for the ER24 emergency service.

"He lost an ear, he lost a number of fingers and toes, he's got very deep wounds, he's got total removal of skin and muscle off his one leg and his one arm, fractures all over the place."

The man was with a group of tourists when the attack took place on Thursday.

"According to eyewitnesses, two chimpanzees grabbed the man by his feet and pulled him under the perimeter fence and into the enclosure," said Jeffrey Wicks, spokesman for emergency service Netcare 911.

He is now in intensive care after undergoing surgery at the Mediclinic Nelspruit hospital.

"He has multiple injuries and is in a critical condition. He is under close observation in the intensive care unit and the next 24 hours are crucial," hospital spokeswoman Liza Pillay told AFP.

The sanctuary, which has temporarily closed after the attack, did not name the man but said he was a graduate student at the University of Texas at San Antonio studying for his masters degree in anthropology and primatology.

Chimp Eden is a sanctuary for rescued chimpanzees, an animal that does not naturally occur in South Africa, and is a joint venture between the Jane Goodall Institute-South Africa and a private park.