The MP said he had "no fears" the decision to allow game hunters into the state's 79 national parks would result in a "free for all" for eratic shooting practices or create extra risks for thousands of visitors who frequent the parks annually.

Shooters will not be allowed to open fire inside the parks until March next year, but angry sentiment since the government passed the practice as law has continued to gain momentum.

Mr Grant was confident the move would be a positive one, which aimed to rid the parks of introduced pests including deer, feral pigs, foxes and wild dogs.

"This is not the free for all being touted by the Greens," Mr Grant said.

"It's a extension of the game and feral animal shooting programs already in place."

But state Opposition Leader John Robertson has accused the government of putting campers and holidaymakers at risk of injury.

"It's a dark day for our national parks ...." he said.

National Parks Association NSW campaign organiser Justin McKee said the program had become a "profoundly emotional" issue for a lot of people.

Mr McKee said by sanctioning the program NSW Premier Barry O'Farrell had effectively drawn people away from the state's major parks.

"Politically and humanely, this is an important issue and one that is really going to hurt him at the 2015 election," he said.

reid.jermyn@fairfaxmedia.com.au