Furious parents have discovered warped videos of cartoon Peppa Pig being watched by their children alongside official clips uploaded to YouTube Kids.
The popular character is depicted as a gangster chasing other characters with knives and guns and setting a house on fire, reports The Sun.
Another depicts Peppa Pig flying a kite with cartoon character Masha. Then a knife-wielding clown appears, traps Masha in a cage and carries her off.
One horrified mother said: "I thought I could safely let my three-year-old watch Peppa Pig on YouTube Kids.
"But when I looked over his shoulder I saw a terrifying witch abducting [Peppa's little brother] George.
"The whole video was vile."
The Sun on Sunday found it took a three-year-old just minutes to find the clips on a computer where the settings were tuned to preschool suitable content.
The child found scores of mock videos featuring Peppa Pig as well as other children's characters, many of which have been watched more than three million times.
YouTube Kids was set up to protect children from inappropriate web content while allowing them to watch suitable content safely.
YouTube have removed the clips and advised that any content that doesn't belong in the app is removed within hours.
Peppa Pig's spider web episode
Last year an episode of Peppa Pig where she befriends a spider was banned in Australia.
After a single complaint, the episode was deemed unsuitable for fear of children getting the wrong idea about touching spiders.