A National Parks and Wildlife Services, NSW Police and Local Land Services surveillance operation has identified people stealing wood from the Murrumbidgee Valley National and Regional Park and Crown lands with further investigations ongoing.

NPWS Manager Park Operations, Robin Mares, said many people will be contacted in the near future in relations to the offences and outlined the damages of such practices.

"These operations found people carrying chainsaws, stealing firewood from the reserves, and driving off tracks which damages bushland," Mares said.

"Taking firewood from the reserves is an illegal activity. The surveillance confirmed some people had covered or switched number plates to try to avoid detection while they were in the parks.

"It's really important that householders make sure any firewood they're buying has been legally obtained, or they could also face fines for possessing illegally cut firewood. Ask the sellers to show proof that the timber has been legally cut and sold.

"Cutting down trees and taking fallen wood from national parks deprives native wildlife of crucial habitats destroying homes for native birds, mammals and reptiles."

There is a hefty penalty for anyone found guilty with the maximum penalty for damaging National Parks estate land is $110,000 or/and six months imprisonment and $1,000,000 for corporations.

Firewood may only be legitimately collected under permit by Riverina residents from the Yarradda precinct of the Murrumbidgee Valley National Park. Firewood collection permit applications can be obtained here or by phoning 6966 8100.