A man has been attacked by a shark on the New South Wales far-north coast.

The 41-year-old was surfing at Belongil Beach at Byron Bay when he was attacked just after 6.30am on Sunday.

NSW Ambulance paramedics treated him at the scene for lacerations to his upper leg, before he was flown to Gold Coast University Hospital in a serious but stable condition.

The man’s friend, Dane Davidson, said the pair had only just paddled out when the shark attacked.

“As soon as my mate got out the back he sat up on his board and instantly a shark smashed from underneath … knocking him clean off his board,” Mr Davidson said.

“There was a lot of splashing and smashing and he started screaming.”

Mr Davidson said he paddled his friend back to the shore.

“We didn’t realise until we were on the beach that there was a big chunk taken out of his leg so there was a lot of blood,” he said.

“I was freaking.

“When I heard the screams he was making in the water and then I saw a chunk of his board floating off, that’s when I realised it was pretty bad.”

Belongil Beach at Byron Bay has been closed for 24 hours. Photo: ABC

Mr Davidson and several bystanders made a tourniquet using board ropes and tied it around the man’s leg.

“He was conscious but … his eyes were drifting around a bit. He seemed a bit dizzy,” he said.

“He was saying his breathing was labouring … overall I think he was all right. He was just in a bit of shock.”

He said his friend was “in good spirits” when ambulance officers took him to hospital and thanked everyone for their help.

Belongil Beach and Main Beach will be closed for 24 hours.

Following a spate of shark attacks in northern NSW, the state government introduced a $16 million shark strategy, including increased aerial surveillance and the use of “smart” drumlines that bait and capture sharks that are then relocated.

NSW Minister for Emergency Services Troy Grant said the government’s shark strategy was to protect those using the ocean “as best we can”.

“It won’t be flawless, and it’s always a concern when somebody is attacked by a shark,” he said.

“These are waters that are their habitat. This is where they swim and live.

“Thankfully this person appears to be OK.”

-ABC