A man has been bitten on the leg by a shark near Byron Bay, on the New South Wales north coast.

The attack happened at a beach between Suffolk Park and Broken Head, just to the south of Cape Byron.

A witness to the attack, Geoffrey Knapp, said the victim was part of a group of surfers in the area.

There were dolphins around that morning swimming with the surfers, Mr Knapp said.

"Just to the north of me I saw the two surfers start to paddle very quickly towards the beach and I thought 'that's a bit strange, maybe they were spooked by the dolphins and they'd mistaken them for a shark,'" Mr Knapp said.

"My friend had waved at me and he also headed to the beach so I knew something was wrong."

"So all four of us headed to the beach."

Mr Knapp said they used the first aid kit from his car to attend to the victim's three puncture wounds on his thigh.

Emergency services also attended the scene, and the man went to Byron Bay hospital.

NSW Police said the 36-year-old man had puncture wounds to his left upper thigh.

He was discharged from hospital after medical treatment of his minor wounds.

Sirens have been used to clear the water and the beach has been closed, but some people have reportedly ignored the warnings.

It is not yet known what sort of shark was responsible, but a 3-metre great white shark was spotted at nearby Wategos Beach soon after the attack.

State government to introduce shark net bill

The beach between Suffolk Park and Broken Head was closed after the shark attack. ( ABC News: Bruce Mackenzie )

Yesterday, hundreds of people gathered at Ballina on the north coast to protest the planned installation of shark nets in the area.

Last month, 17-year-old Cooper Allen was bitten on the upper thigh while surfing at Lighthouse Beach at Ballina on the NSW north coast.

Cooper was helped back to shore by a friend he was surfing with and his injuries were not life threatening.

Today, the NSW Government said it would introduce a bill to Parliament next month to start a six-month trial of shark nets on the north coast by the summer school holidays.

Primary Industries minister Niall Blair said the Government would create legislation to regulate the use of mesh nets so a trial could begin as soon as possible.

"Making sure the north coast is a priority for this trial is what we are concentrating on," he said.

"We do have nets between Newcastle and Wollongong and they have proved to be successful. That's why we are extending that to a trial on the north coast for six months."

Mayor still opposes shark nets

The Byron Shire Mayor, Councillor Simon Richardson, said the NSW Government continued to ignore calls for funding shark-safety measures other than nets in the area.

The area has warning signs about snakes, but not about sharks. ( ABC News: Samantha Turnbull )

He wants financial support for a number of measures the council has been taking to protect swimmers and surfers.

"The council recently paid for, itself, with no state government support, a shark-spotting program," Cr Richardson said.

"It was highly successful, we've asked again for support to trial beaches including Broken Head, we've asked for support for a year-and-a-half to use gyrocopters.

"So I think the community is getting a little bit frustrated that what independent research commissioned by the State Government has said — and that the Byron Council is doing — is being ignored."

He is standing firm on his position opposing shark nets, but will be guided by the community.

"I don't think [shark nets are] for Byron, but we can all wait and see if there's a huge community outcry for it," he said.

"I think it's important that we look to solve the problem rather than just emotionally respond to it."

Labor wants shark nets installed tomorrow

The Labor Party's NSW north coast spokesperson, Walt Secord, is in favour of shark nets and wants them installed immediately.

"I think they should be in as early as tomorrow," Mr Secord said.

"The State Government promised months and months ago, they held a shark summit a year ago, they said they were going to write to the Prime Minister about a month ago.

"It is time they stopped making excuses and got those nets up."