A monkey was pelted with stones, shot at and burned to death in a South African township because residents believed it was linked to witchcraft, an animal welfare agency has said.

A mob chanted "Kill that witch!" as the vervet monkey was put in a bucket, doused with petrol and set on fire, according to witnesses. Children who witnessed the killing last week were said to be traumatised.

One resident, Tebogo Moswetsi, admitted he had captured the monkey as it sought refuge up a tree in Kagiso, west of Johannesburg.

"I was curious to see this monkey that people claimed could talk, and when I saw a group of people chasing after it, I joined them," he told South Africa's Star newspaper. "When it went up the tree, I climbed after it and brought it down because I was curious as I found it unbelievable that a monkey could talk.

"I feel guilty. I shouldn't have taken it down from that tree. I dropped it down after someone poured petrol on it. I had no choice."

Moswetsi added: "Someone struck a match. [The monkey] got out of the bucket and dropped down dead. They continued throwing stones at it."

Cora Bailey, manager of Community Led Animal Welfare (Claw) in South Africa, was alerted by a local resident and arrived at a scene of "sheer criminality".

She said: "We just got there too late. What was incredibly sad is that there were so many little children in the crowd – some of them very traumatised.

"There were youngsters literally laughing in my face. But there were older people who were devastated by it. Everyone was saying sorry. While I was talking, the monkey was burning behind me."

Bailey said there is a "dreadful superstition" about monkeys and witchcraft in some communities, fuelled by ignorance that the animals can become separated from their troops or displaced from their natural habitats.

"We deal with this kind of situation on a very regular basis. We usually manage to do crowd control so the monkey doesn't come to any harm."

Bailey said she was horrified by racist comments that have appeared online in reaction to the incident. "Every time this happens, it's people in the community who call us. Cruelty to animals is not a racial thing. I've worked in townships for 20 years and there are good and bad people in all communities."