Wagga Wagga City Council confirmed on Wednesday it had discovered the carcasses and said it believed the slaughter operation had been going on for a “long period of time”.

The investigation into the property first began out of concern horses were being left in a dry creek bed, the council said in a statement.

“The information led to council entering the property supported by members of NSW Police, the NSW food authority, local land services, the department of primary industries and racing NSW,” the council said.

“Initially, the focus of the investigation was the confirm whether the carcasses had been left in the dry creek bed and possible offences under the protection of the environment operations act.

“Once the inspection of the property commenced, it became clear that the slaughtering of horses had been occurring for a long period of time.

“Numerous separate dumps of carcasses were discovered at locations throughout the property.

“It is estimated that there are in excess of 500 horse carcasses. Some of these carcasses were no more than skeletal remains, while others were killed relatively recently.”

NSW Police and other government agencies were now collecting evidence for possible offences.

It is unclear if the knackery is a legal or illegal operation.

NCA NewsWire understands the property is owned by a Wagga Wagga local, but the part of the property on which the carcasses were found had been leased out to another man.

Racing NSW told NCA NewsWire the man running the allegedly makeshift slaughterhouse was placed on an “excluded persons list” in late 2022, banning him from the industry.

The blacklist means participants in NSW racing are not permitted to provide horses to the man.

Racing NSW also told NCA NewsWire the horses found at the property were not thoroughbreds, or horses bred for racing.

Nationals Member Wes Fang called the discovery “incredibly concerning” and said he had been told some of the horses might be rehomed brumbies.

“The NSW government needs to be forthcoming as to the circumstances behind its establishment, operation and for what purpose it operated,” he said on Wednesday.

“Staff from the Wagga Wagga City Council, NSW Police and the NSW EPA inspected the property on Monday, and we are hearing a number of horses may be rehomed brumbies.

“If this is the case, the National Parks and Wildlife Service and RSPCA need to immediately be involved in the investigation.

“We have always had concerns about the lack of transparency around the Minns Labor government’s management plan for brumbies in Kosciuszko National Park and this incident has reaffirmed those concerns.”

The government is pursuing new control strategies for brumbies in the park to suppress a population boom in the horses.

NSW Environment Minister Penny Sharpe and the NSW Environmental Protection Agency have been contacted for comment.