Forest officials said the monkeys might have been poisoned because several watermelons and jaggery cubes were also found at the site.

Police are investigating if the food items were laced with poison.

A case has been registered and the cause of their death is being probed, the police spokesman said.

The carcasses of the monkeys have been sent to the Indian Veterinary Research Institute (IVRI) in Bareilly for autopsy, forest officials said.