A man has been seriously injured in a shark attack at a beach south of Port Macquarie on the New South Wales mid-north coast.

Ambulance New South Wales said paramedics responded to reports a bodyboarder had been attacked at Lighthouse Beach, south of Port Macquarie, shortly after 5:00pm on Saturday.

The 38-year-old was helped out of the water and treated at the scene by paramedics for stomach and back injuries initially considered life-threatening.

He was taken to Port Macquarie Hospital, where he is now in a stable condition, and was expected to be flown to Sydney on Sunday, according to Surf Life Saving New South Wales.

All beaches in the area have been closed for 24 hours. Signs have been erected and people are urged to stay out of the water until further notice.

The Department of Primary Industries (DPI) has initiated its Shark Incident Response Plan following the attack.

They have sent a staff member to Port Macquarie to identify the shark type from the bite pattern and forensic information.

Four beaches in the Evans Head and Ballina area were closed earlier this month following the fifth attack in the region in less than a year.

Surf Life Savers Emergency Coordinator Jimmy Keogh said the decision was made due to large quantities of bait fish in the area.

The string of shark attacks prompted claims the State Government failed to protect beachgoers.

The DPI said $100,000 has been put aside to trial new preventative measures, but it could still take many more months for trials to begin and be adopted permanently.