A group of concerned citizens said the dogs found washed up to the beach were free from physical injuries, indicating the likelihood of poisoning.

Last month alone, fishermen and beach workers found 15 dogs, with some saying they found at least three carcasses a day.

Aida Redza, a member of a local action group, said that for the past three years, dead dogs had been dumped into Sungai Kelian, a river that flows out to the beach.

She said the some of the carcasses were wrapped in plastic and some in cloth.

“It is a mystery,” she said. “Are these poor dogs poisoned or cruelly killed? A beach cleaner has been telling us that he has encountered many dead dogs at the beach for the past two to three years. He has buried some on the beach.”

Aida said the Penang Island City Council and the veterinary services department had said the matter was not under their jurisdiction.

She was told that the issue was likely under the drainage and irrigation department, since the dead dogs may have been dumped at a river nearby.

Veterinary officers told them they could not carry out post-mortem examinations since animal abuse had not been confirmed.

Aida said a police report was lodged, including a city council complaint. The police referred her to the veterinary department while the council referred her to the health department

She said residents had floated a theory that these were strays that had accidentally eaten poisoned food meant for crows.

Sarah West, the secretary of an organisation called Spay Adopt Manage Assist, said there was a need to increase the number of CCTV cameras near a bridge over the Sungai Kelian river.

She said it was possible that people responsible for disposing of dead dogs through cremation were taking the easy way out by dumping the carcasses into the river.

She added: “Fishermen here say this has been going on for years. I suspect someone is doing this for a living.”

When contacted, City councillor Connie Tan said portable CCTVs are being considered to nab the culprit behind the dog dumping into Sungai Kelian.

“The council is taking this issue seriously and will use our resources to assist the veterinary department in this investigation. Also eyewitnesses of improper disposal of animal carcasses can lodge their complaints by calling 04-508 4368 or via online at https://akh.dvs.gov.my.”