Sinister note attached to pet cat which returned home tightly bound with cable ties

The RSPCA is investigating after a pet cat was found bound with cable ties along with a sinister note in Melbourne, Australia.

The owner said they let their cat outside in the morning, with it returning two hours later with cables ties tightly bound its neck, tail and leg and covered in a green substance, believed to be spray paint, ABC reports.

The pet cat returned home bound "very tightly" with several cable ties. Photo / RSPCA Victoria

A note attached to the cat's neck read, "Keep your cat locked up or else".

Inspectors from the RSPCA Victoria are now investigating the horrible act.

RSPCA inspector Karen Collie said the cable ties were "extremely tight" and could have caused permanent damage to the cat.

"They were restricting the blood flow in those areas," she said.

"If they'd been left and not removed and restricted the blood flow for an extended period of time, that may have started to cause death in the tissues underneath."

This threatening note was found attached to the cat's neck. Photo / RSPCA Victoria

RSPCA Victoria are now investigating. Photo / RSPCA Victoria

She also said such cases of cruelty are reported regularly, in Melbourne.

"Unfortunately, we do receive regular reports of abuse to cats that have wandered away from home," Collier said.

"They are often subjected to cruelty such as illegal traps, being locked in sheds or under houses and being shot with rifles or bows."