A research diver from the United States was mauled by a shark off the Rocky Bay coast near Durban on Tuesday, Netcare 911 said.

The 22-year-old man's left leg and both hands were “badly” mauled, spokesman Chris Botha said.

The man was diving on the Aliwal shoal, watching sardines, when he was bitten by the three-metre dusky shark just after noon.

“There is always a danger that the predator will mistake a diver for part of their meal when (the shark) goes into a feeding frenzy,” Botha said.

The skipper of the boat “definitely saved the young man's life” by lifting him from the water and stemming the flow of blood.

Paramedics stabilised the injured man before he was airlifted to the Albert Luthuli Central Hospital in Durban.

He underwent surgery in the afternoon and may need further operations, Botha said.

The US embassy had been alerted to the incident and would kept updated on the man's condition, Botha said. -

Sapa