Wagga City Council has revealed it was leading a joint investigation - which also involves NSW Police - following reports horses had been butchered at the property and their carcasses left in a dry creek bed.

In a statement issued on Wednesday afternoon, general manager Peter Thompson said information received led council staff to enter the property alongside representatives from the police, the NSW Food Authority, Local Land Services, the Department of Primary Industries and Racing NSW.

"Initially the focus of the investigation was to confirm whether the carcasses had been left in the dry creek bed and possible offences under the Protection of the Environment Operations Act," Mr Thompson said.

"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," Mr Thompson said.

"Once the extent of the operation had been identified, NSW Police and other state government agencies began collecting evidence for possible offences and regulatory actions under a range of NSW state government legislation."

The council said the matter remains a current investigation and it would not be providing further comment at this time.