In a letter to NSW Minister for Energy and Environment Matt Kean, Mr Barilaro said the proposed cull of 4000 brumbies, due to get underway next month, was a "causing great distress within the local community".

Mr Barilaro, who is also the Nationals state member for Monaro, said the wild horse population in Kosciuszko National Park had been affected by the recent bushfire season and called for a new survey.

"In my region the brumbies are cherished and there is no doubt that the population of wild horses are also significantly impacted," he said.

"This is on top of the drought that also saw many horses perish and the numbers decimated."

The Invasive Species Council said Kosciusko National Park was under pressure from brumbies and the NSW government had failed to act effectively and humanely to control the population.

"The current NSW trapping program is extremely costly, inhumane and ineffective. It has been unable to even stabilise the population, let alone reduce it," it stated on its website.

"Feral horses trample and eat large amounts of alpine and sub-alpine plants, foul wetlands, erode streams, spread weeds, create a vast network of tracks and threaten the safety of motorists."

It said brumbies in the park increased by 23 per cent each year despite trapping.

Mr Barilaro has been a driving force behind the protection of wild horses for some time. Last year, a petition to give brumbies heritage status sparked heated debate in parliament before being voted down.

Mr Kean had previously said it was important to listen to the science, and that feral animals including horses were one of the biggest threats to national parks.

Mr Barilaro claimed the December 2019 aerial survey of wild horse populations in the park was "questionable" and called for a new survey to be undertaken before any culls.

That survey estimated there were 19,000 wild horses in the park.

"There is strong scientific evidence that [wild horses] are damaging the park's fragile alpine and sub-alpine environment," he said.

"If the population is not carefully managed, we risk unacceptable impacts to the environment and cultural values of the park."