A troop of 22 monkeys, most of them infants, were found poisoned in a house in Umdloti in KwaZulu-Natal – 13 of them have since died. It is believed they were given bread laced with pesticide. The surviving monkeys are being treated.

Monkey Hotline founder Steve Smit said the primates were found in a horrifying state – “lying all over the floor, foaming at the mouth, with some hanging off a tree convulsing”. Smit said it was a “malicious and deliberate” act.

Animal activists have put up a $2800.00, (£2100.00) reward for information leading to an arrest in the case.

David Barritt, chief campaigner for Network for Animals (NFA) said monkeys are widespread in some areas of South Africa and many other countries and that local people often consider them pests. “Monkeys are skilled thieves and if they can gain access to homes, they love to help themselves to fruit and other food. This is something you have to accept if you are lucky enough to live in an area where monkeys roam free,” he said.

“To kill them in this way is absolutely sickening, the kind of wicked cruelty that NFA fights every day.”

Barritt urged people to use non-lethal methods to discourage monkey raiders. “The simplest solution is to make sure monkeys can’t get into homes by using window and door screens,” he said.

There are no accurate statistics on how widespread animal poisonings are in South Africa, but it is believed to have increased considerably over the years.