The Agri-Food and Veterinary Authority (AVA) is probing a case of pet negligence after nine cats were found in deplorable conditions in a Boon Lay rental flat.

The Cat Welfare Society (CWS) wrote in a Facebook post on Thursday that it was told about the case on Dec 29 last year, and a mediator had immediately reported it to various agencies.

On top of the terrible conditions, the nine cats had no food, CWS said.

In response to queries, AVA said yesterday that it was investigating the case.

The society said the tenant of the flat subsequently abandoned the animals in the void deck, and this was spotted by a volunteer who had been feeding them daily through a gap in a window.

The cats, which were not sterilised, were found "shivering in fear downstairs", said CWS.

A resident has adopted two cats while the remaining seven were impounded. AVA is working with CWS to rehome them.

Anyone with information on the case, such as photos or videos, can contact AVA on 1800-476-1600. All information provided will be treated as confidential, it said.