A WA fisherman has described the moment he had to fend off a suspected white shark while diving off the Burns Beach coast on Saturday morning.

Joe Petrovich was diving from a boat about two kilometres offshore at 9.30am when he spotted the 4.5-metre shark circling him.

Joe Petrovich had his fin bitten off by a white shark while diving off the coast of Burns Beach. Credit:Facebook

Mr Petrovich told Nine News Perth reporter Kelly Haywood that the ordeal lasted at least five minutes.

The avid fisherman said he managed to spear the shark in the face to get away but it came back for a second time and took a chunk out of his flipper.