The charity 7th Heaven Animal Rescue Trust, based in Newtownabbey, said kittens had been beaten and even hanged in the Yorkgate area of north Belfast.
The Cats Protection League confirmed that they had been contacted on Thursday by a woman who reported seeing "kittens being swung by their tails or tied up and beaten by some youths" in the area.
"As a result, two Cats Protection volunteers visited the area that evening and managed to trap an injured kitten and take it to the vet, where it is now receiving veterinary care," a spokesperson said.
One kitten was taken to a vet after one of the adoption centre's volunteers found the injured animal.
The charity said they could not confirm if it was one of the same kittens reported to them, but they said it was likely that this was the case and they have reported the incident to the PSNI and the local animal welfare officer.
A spokesperson for Belfast City Council confirmed they had received report that kittens had been tied up in the North Queen Street area.
Andrew Doherty, Deputy Manager at Cats Protection's Belfast Adoption Centre, said: "Naturally we are appalled by this reported act of cruelty.
"As the UK's leading feline welfare charity, Cats Protection is completely dedicated to cats and their care so when we take in cats or kittens that have been mistreated, it is absolutely heart-breaking.
"We would urge anyone with any information about these incidents to contact the PSNI or the Animal Welfare Officer for Belfast via Belfast City Council. It is vital that we all do that we can to ensure that these terrible acts do not go unpunished."
Seventh Heaven Animal Rescue Trust has appealed for the cats to be found as young kittens need to be kept with their mothers.
They have also asked for anyone willing to foster any animals recovered to contact them.