This sickening footage shows a man offering food to a friendly monkey before slapping it hard in the face.
The thug reached out his hand towards the langur monkey, sitting in Mandore Gardens in Jodphur, India, then hit it and ran away.
His friends can be heard laughing in the background as the monkey falls backwards onto the floor.
Mandore Gardens attracts thousands of tourists who come to see its memorials to Jodhpur's former rulers, known as dewals.
Kieran Harkin, Head of International Wild Animal Campaigns, told MailOnline: "This video shows a sad and shocking case of cruelty.
"The footage is both brutal and totally mindless.
"Sadly cruelty like this still occurs but it is important to spread the message that this sort of behaviour is unacceptable and barbaric.
"We also urge online platforms such as YouTube to take responsibility for content posted on its pages to ensure animal abuse is never posted as a form of so-called entertainment."
The video was uploaded onto a YouTube comedy channel.
Harkin, whose charity raises awareness about animal cruelty, added: "The fact that it is being presented as a funny piece of content is even more alarming."
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