An Australian state government has decided to legally protect rather than kill thousands of wild horses, infuriating scientists who argue the feral species is doing severe environmental damage to the country's iconic Snowy Mountains alpine region.

New South Wales Deputy Premier John Barilaro said on Monday that his government had struck a balanced response to ecological concerns about the impact of the horses, known as brumbies, on Kosciuszko National Park.

A 2016 government report had recommended that 90 percent of the park's 6,000 brumbies be killed, reducing the herd to 600 in the 6,900 square kilometers (2,700 square miles) of mountainous wilderness that includes Australia's highest mainland peak, Mount Kosciuszko, and the nation's most popular ski fields.

Mr Barilaro said legislation will be introduced to state parliament this week that will recognize the heritage value of the brumbies to the park and ban killing them. But brumbies will be relocated from environmentally sensitive areas.

"There is no clear answer. For all the people who are happy today, there'll be some who won't be," Barilaro told Australian Broadcasting Corp.