A CONTROVERSIAL law that will allow hunters into national parks has been passed by New South Wales Parliament following hours of fractious debate.

The Shooters Party's changes to the Game and Feral Animal Control Act passed both the upper and lower houses today, allowing recreational hunters to cull feral animals in 79 national parks and reserves.

A day after the Shooters Party's Robert Brown said it was "unfortunate" he couldn't beat the upper house Greens MP Jeremy Buckingham to death, government and opposition MPs traded barbs in the Legislative Assembly.

Former Labor premier Kristina Keneally described the laws as "a dirty political deal and stupid policy", with the sole aim of garnering Shooters Party support for the government's power privatisation.

"This bill is about the politics of a premier who can't get his way in any other manner except to go back on his word and put our national parks at risk," Ms Keneally said.

"We are here in the lower house debating about amateur shooters to roam our national parks with loaded guns because Barry O'Farrell can't get his electricity sale through the parliament in any other way."

Opposition Leader John Robertson said the bill was a "straight out broken promise", after Premier Barry O'Farrell had said he wouldn't allow hunting in national parks.

"This bill is not going to make one difference to the number of feral animals in our national parks," Mr Robertson said.

"What it will do is compromise the safety of every single person in our national parks, compromise the flora and fauna in our national parks."

Critics have raised fears the laws will open hundreds of parks and reserves to recreational hunters, with Environment Minister Robyn Parker given the power to veto or approve shooting sites.

Ms Parker told MPs in the lower house that parks would not be opened to recreational hunters during an open hunting season like in New Zealand.

"We will be extending the current controlled and safe program of eradicating feral animals, which wreak havoc in our national parks," Ms Parker told parliament today.

"This in anyone's language is not recreational hunting.

"There will be penalties in place that will be brought down very hard on those that think ... they can get out there and shoot at whatever they see."

Nationals MP John Williams said Sydneysider MPs against the legislation had no idea about the trouble caused by pests in rural areas.

"It really does amaze me that we have seen speakers from the concrete jungle of Sydney telling us how it goes on in the country," Mr Williams said.

"We continue to listen to the member for Marrickville (Carmel Tebbutt) whose biggest trip is to go to the shopping centre on a Saturday morning."

On Wednesday night Mr Brown threatened Mr Buckingham with violence after being repeatedly goaded by the Greens MP during the upper house debate.

"Unfortunately we're in a modern era so I can't take you outside and beat you to death."

A contrite Mr Brown later apologised for the outburst.

Originally published as Laws pass to allow hunting in national parks