A volunteer at a US animal sanctuary has died after he was savaged by a 1,000-pound liger - a rare cross between a lion and a tiger.



Peter Getz, 32, suffered fatal puncture wounds in his neck and back as Rocky, who weighs twice that of an ordinary lion and is 20 times more powerful than a human, pounced on him during feeding time.



An investigation was under way last night into why Mr Getz, an accomplished big cat keeper, broke with protocol and entered Rocky's enclosure at Safari's Animal Sanctuary in Broken Arrow, Oklahoma.



Bleeding heavily, he hauled himself out of the enclosure with help from two fellow keepers but collapsed outside and was airlifted to hospital, where he died last night.



"This is just horrid," said the sanctuary's owner, Lori Ensign.



"We try to have all the procedures in place but for some reason they weren't followed this time. In all my years we've stressed that whatever you do, don't open that gate."



Rocky, who came to the sanctuary from a zoo in North Carolina that closed because it went broke, is so powerful that his toys were bowling balls and he would ordinarily be fed fresh meat via a pole poked through the fence.



But Ms Ensign also stated that when Rocky was younger, she would ride on his back and that he was playful and gentle. Pictures on her website show her walking a tiger on a leash and bottle-feeding a cub.



Animal Planet host and wildlife expert Jeff Corwin said yesterday: "You're talking about an animal that is 20 times more powerful than the human that was feeding it.



"This animal could have, by its nature, a very individualistic, nice, personality...but one bad moment can be critical, if not lethal, to a human being."



Ligers are a cross between a male lion and a female tiger and are the biggest of all big cats.



The non-profit Safari's sanctuary is run by volunteers and regulated by state wildlife officials, who were investigating last night.



They will determine whether Rocky will have to be euthanised. Eight years ago, a bear was reportedly put down after biting keepers at the refuge, which is home to around 200 rescued animals.



Mr Getz had volunteered there for over a year and had previously worked at Tulsa Zoo.



Dr Dan Danner, a local veterinarian who knew both the keeper and the liger, said: "Rocky is a big old baby, but if you've got an offensive lineman and they get excited, they are going to chomp a little harder and get aggressive."