Chimpanzees at a South African sanctuary mauled an American researcher which left him in intensive care on Friday.

Two chimps reportedly bit the victim and dragged him nearly half a mile that led to loss of his fingers and part of an ear.

Andrew Oberle, the victim was giving a lecture at the Jane Goodall Institute Chimpanzee Eden when he was attacked, said a witness. The chimps suddenly pulled him into their enclosure by his feet and dragged him.

Oberle, an anthropology student at the University of Texas, was pursuing a research at the sanctuary when he was attacked.

Oberle's mother said he was quite passionate about chimps, right from his childhood and said he was completely aware of the dangers involved in dealing with the animal.

According to an Associated Press report, the emergency worker Jeffery Wicks said Oberle suffered multiple and sever bite wounds. The hospital where Oberle was admitted said he was still in a critical condition and had undergone a surgery after the attack.

The sanctuary staff plunged into action as soon as Oberle was attacked by the chimps. Tourists were immediately taken off to a safe place while the sanctuary people fired into the air to scare the chimps.

The sanctuary was closed for a short while after the attack. Both the chimps have been kept in their night enclosure until the on-going investigations are over.

"The safety of our visitors and staff is paramount. We have never had an incident like this, and we have closed the sanctuary to investigate how we can ensure it will not happen again," AP quoted the institute's executive director David Oosthuizen as saying.

The sanctuary was founded by the celebrated primatologist Jane Goodall in 2005 and has been a home for rescued chimps mainly from North Africa.

The chimps had suffered severe abuses from humans. In North African chimps are hunted for their meat and also to be kept as pets.