Wellington  - A man attacked while swimming off a New Zealand beach was injured by a stingray, not a shark, as police and paramedics first thought, according to news reports on Sunday.

Police cleared beaches on the South Island's Tasman Bay on Saturday, after Mike French, 46, a builder, staggered from waist-deep water at Kina Beach with two deep, tearing lacerations in his back.

He did not see what attacked him but paramedics told police the wounds looked like a shark bite and bathers were told to keep out of the water.

French was flown by helicopter to Nelson hospital where he underwent surgery. (dpa)