Surfer whose leg was bitten off by a shark has the limb reattached after his limb washed up on the beach

A young surfer who lost his leg while fighting off a shark on a remote beach has undergone surgery to have his limb reattached after it washed up on the beach.

Kai McKenzie was catching waves at North Shore Beach, near Port Macquarie on the NSW mid-north coast, when he was attacked by a suspected three-metre white shark on Tuesday morning.

After paddling to shore, the 23-year-old was saved by a quick-thinking off-duty police officer who used his dog's leash to stem the bleeding.

The surfer's severed leg washed ashore where it was put on ice by a growing crowd of onlookers and rushed to hospital under police lights and sirens, NSW Police said.

Mr McKenzie and the leg were both airlifted to hospital, where he has now undergone surgery to reattach the leg, Nine News report.

Kai McKenzie, pictured, was surfing at North Shore Beach on the NSW mid-north coast when he was attacked by a shark

Kai McKenzie, pictured, was surfing at North Shore Beach on the NSW mid-north coast when he was attacked by a shark

Mr McKenzie fought off the shark and caught a wave back to shore with serious leg injuries and a chunk bitten out of his surfboard

Mr McKenzie fought off the shark and caught a wave back to shore with serious leg injuries and a chunk bitten out of his surfboard

An off-duty police officer used their dog's leash as a makeshift tourniquet until paramedics arrived

An off-duty police officer used their dog's leash as a makeshift tourniquet until paramedics arrived

The 23-year-old lost his leg in the attack, which washed ashore where it was put on ice by a growing crowd of onlookers

The 23-year-old lost his leg in the attack, which washed ashore where it was put on ice by a growing crowd of onlookers

After assessing photographs of the injuries, NSW government shark biologists believe a three-metre white shark was involved in the attack and inflicted 'severe injuries' to the surfer's right leg.

He is believed to have fought off the shark and caught a wave back to shore suffering severe blood loss and a chunk bitten out of his surfboard. 

Initial beach closures have ended, Port Macquarie Hastings ALS Lifeguards said in a statement on Wednesday. North Shore Beach is isolated and largely accessible only by a dirt road.

Mr McKenzie's devastated loved ones previously spoke about how he may never walk normally again

A GoFundMe page organised by Mr McKenzie's neighbour, Lauren Mac, said the young surfer was at John Hunter Hospital, noting it would be a 'long road to recovery'.

'He saw the shark approach and was able to fight it off but suffered a severed right leg,' the page reads.

'Clinging to life, he was able to catch a wave back to the beach.

'Please dig deep for this family to assist with Kai's recovery and rehabilitation.'   

Ms Mac said the prospect of losing his leg was a shocking blow to the young surfer who had only just returned to the water after fracturing his neck.

'His mum and dad told me it's going to be a long road to recovery regardless of the outcome,' she said.

More than $70,000 had been raised on Mr McKenzie's behalf since the page was set up on Wednesday morning.

McKenzie was attacked by a shark at North Shore beach in Port Macquarie on Tuesday

McKenzie was attacked by a shark at North Shore beach in Port Macquarie on Tuesday

Mr McKenzie (pictured) is understood to have arrived at the isolated beach with a friend after he caught a ferry

Mr McKenzie (pictured) is understood to have arrived at the isolated beach with a friend after he caught a ferry 

Members in the surfing community have also wished him a speed recovery, including his sponsor Rage

Members in the surfing community have also wished him a speed recovery, including his sponsor Rage

The off-duty cop used his dog's lead as a tourniquet to stem the bleeding from the wounded areas after the young surfer was attacked by the shark (stock image)

The off-duty cop used his dog's lead as a tourniquet to stem the bleeding from the wounded areas after the young surfer was attacked by the shark (stock image)

His aunt Michelle McKenzie said the young man was 'an incredible surfer, skater, musician, videographer and all-round legend'.

'He has always lived life to the fullest squeezing every minute out of the day,' she wrote in a Facebook post on Wednesday afternoon.   

'Yesterday he was attacked by a shark at Port Macquarie, doing what he loved ... he suffered life changing injuries.'

The accomplished surfer, who had several sponsors, was only recently back in the water after suffering a significant injury.

'So happy to be back surfing after having a fractured neck,' he posted on Instagram in January.

Members in the surfing community have also wished him a speed recovery, including his sponsor Rage who shared a heartfelt Instagram post.

'Sending love to Kai, the youngest RAGE boy on the team and the toughest person that we know,' it read.

'Yesterday he was attacked by a shark and has lost his leg while surfing in Port Macquarie.

'He has been through a lot, breaking his back (neck verterbrae) last year. He never once complained always just got with doing what he loves as soon as possible. He is an inspiring person.

'The whole rage gang loves you man and we will see you soon.'