A 65-year-old man who was bitten by a shark while he was surfing on the Mid North Coast of New South Wales is "quite happy" and in stable condition.

Police said the man was attacked just off Booti Booti after 9:00am, by a shark later confirmed to be a great white.

He managed to swim to shore and contacted emergency services.

The man said the shark snapped his board in two and then dragged him under. ( ABC News )

He was treated for puncture wounds to his arm and leg and airlifted to John Hunter Hospital in stable condition.

The Department of Primary Industries (DPI) said its assessment confirmed a great white shark was responsible for the attack.

Graham Nickerson, from the Westpac Rescue Service, said the victim was in good spirits despite his ordeal.

"Apparently the shark came up under his board, snapped his board in two and then dragged him under by the leg rope," Mr Nickerson said.

"He's quite happy … considering what he's been through, but he's got pretty severe lacerations to his lower limbs, but he's in a stable condition."

The man was surfing on this board when he was bitten by the shark. ( Fairfax Media/Newcastle Herald )

Mr Nickerson said the surfer was already thinking of returning to the ocean.

"He did mention to us that he needs another surfboard, which is pretty evidenced when you see the pictures of the surf board snapped in two with a large bite out of it," he said.

The beach has been closed until further notice.

The Government ordered smart drumlines be set up off the beach as soon as possible.

The beach at Booti Booti was closed after the shark attack. ( ABC News )

The DPI's Shark Smart app recorded four sightings of great whites yesterday morning, 10 kilometres to the north, at Forster.

The Shark Smart app showed reports of several sightings at Forster yesterday. ( ABC News )

Marine biologist Daniel Bucher, from Southern Cross University, said it was not possible to say whether the shark detected by the app yesterday was the same shark that attacked today.

"If it goes off as it has been over the last few weeks, we don't know whether that's one shark swimming in circles or a whole bunch of them coming through," he said.

Associate Professor Bucher said the location of the attack fit with shark migration patterns.

"The Shark Smart app has been showing regular sightings of white sharks around the Forster area and very few, in fact none at all, in the last few weeks up around the north coast, so we tend to get this contraction of the white shark population further south as the water warms up," he said.