Feral horses constitute a "key threatening process" that pushes dozens of species at risk closer to extinction, according to an independent scientific panel set up by the Berejiklian government.

The final determination of the NSW Threatened Species Scientific Committee also comes as conservation groups announced they will boycott a call for nominations for the Wild Horse Community Advisory Panel to show their opposition to the government's decision to protect the animals in the Kosciuszko National Park.

Wild brumbies in the Kiandra region of the Kosciusko National Park. Credit:Andrew Plant

The scientific committee noted the horses were an introduced species, with the first recorded escape into the wild coming in 1804, 16 years after the First Fleet's arrival. The wild horse population now numbers as many as 400,000, mostly in central Australia, with more than 6000 in the Kosciuszko National Park as of 2014.

The horse population also had the potential to increase in good seasons, with those in the Victorian East Alps rising by 22 per cent a year between 2003 and 2009.