Fourteen-year-old Lydia Ward said she was at a beach near the southern city of Invercargill when the shark struck.

The shark, about 1.5m (4.9ft) in length, is reported to have lunged at her and tried to bite her hip.

Standing in water that only reached up to her waist at Oreti Beach, she said she hit the "big, grey, slippery thing" repeatedly with her body-board.

"I showed Dad and he didn't really believe me but then I showed him my wetsuit with all the blood coming out and he believed me,"

Although not seriously injured, Lydia required hospital treatment for two of the deeper wounds.

Her mother told a local newspaper that Lydia thought she had accidentally stood on the shark before it had attacked her.

She said neither Lydia nor her 15-year-old brother, also in the water at the time of the attack, planned to go back into the sea in the very near future.

Shark attacks are very rare. Researchers say that more people die from bee stings and lightning strikes than shark attacks.