A French tourist is recovering in New Zealand after a shark mauled her leg while she was bodyboarding at a remote beach in Porpoise Bay.

The woman, believed to be in her 20s, was dragged onto the beach by her friends who used towels to stauch the bleeding.

Catlins Surf School owner Nick Smart told the Associated Press he had finished instructing surfers when the shark attacked.

"I saw somebody running and instantly had a very strong feeling that things were not right," he said.

Smart drove several metres down the beach to where the woman lay.

"She handled it really, really well," Smart said. "She was calm, not at all hysterical. I assured her she wasn't going to die, and that a helicopter would be coming. She was in a bit of shock."

Smart said he brought a stretcher to the woman and they moved her to a beach house while they waited about 40 minutes for a helicopter to arrive.

The woman was flown about 160 km (100 miles) to Dunedin Hospital.

Shark attacks are uncommon in New Zealand. In 2013, a 47-year-old man died after an attack at a popular tourist beach west of Auckland.

Until then, there had only been around a dozen shark attacks in more than a century.