A surfer is recovering in hospital after being attacked by a shark at a remote beach on the New South Wales mid-north coast.

The 29-year-old was surfing ear Diamond Head, south of Port Macquarie, when he was attacked by what is believed to be a bull shark shortly before 11.00am (AEDT).

Ambulance spokeswoman Michelle Hoctor says the man was bitten on his right hand and leg.

"We've arrived to find this patient has lost an index finger and a knuckle on his right hand and he has suffered a large bite to the right thigh," she said.

The man was given pain relief and fluids at the scene before being taken by rescue helicopter to the John Hunter Hospital in Newcastle.

He is now in a stable condition.

His family has issued a statement thanking members of the public, paramedics and other emergency officers who offered rapid assistance on the beach.

Nearby patrolled beaches at Crowdy Head and North Haven have been closed as a precaution.

Surf Life Saving spokeswoman Donna Wishart says shark attacks in the area are uncommon.

"It's always surprising to have a shark attack because there is such a low risk generally of shark attacks, but it's not uncommon in that area for shark activity," she said.

"If people could swim at patrolled locations it at least gives us an opportunity to get people clear of the water if there is a shark in the vicinity."