A mom has told of her horror after her daughter downloaded an app based on a TV cartoon which makes a chilling prank call — threatening to knife children.

The free Google Play app is called “Call Blaze and the Monster Machines 2018” but does not appear to have any official links to the show, which is on Nickelodeon.

Jane Diya, 34, discovered the disturbing feature when the app was downloaded by 7-year-old daughter Samantha Higgins.

A video she took shows the app making a call to her phone before a sinister voice says: “Hi kids, I’m your new friend Happy Slappy, or whatever you want me to be called.

“You see I want to play with you kiddo, maybe we could perform some fun games together. What’s this hogwash. You look afraid. Is it this knife in my whirly twirly hands? Making you a little nervous huh?

“That’s all right ’cause this knife is gonna improve your look — when it’s sticking right out of you. Ha ha ha ha ha.”

Google has now pulled the android app from the Play store.

Diya, from England, said: “I was absolutely livid when I heard it.”

“If she had heard that before me there would have been absolute hell on. I was completely furious.

“It is so creepy. To hear a call come from a phone on a kids app threatening to knife a child — I could barely believe my ears. It’s completely unacceptable.”

The TV cartoon “Blaze and the Monster Machines” features an 8-year-old called AJ who drives a monster-truck called Blaze.

Diya said her daughter asked to download the app, so she agreed, but thankfully checked it before her daughter played it herself.

It appears to let kids play a block-matching game and then rewards them with a “call,” when a phone appears on the screen.

When answered the app plays the creepy message.

Jane said her daughter heard the message herself when her brother Steven Varela, 13, played the message after his mom made the discovery.

“She didn’t sleep well at all last night because of it,” she said.

“I don’t see how Google can allow this app to be on there.”

Google said the app had been suspended.

A Google spokesman said: “We have a set of policies designed to provide a great experience for users and developers and we act quickly to remove apps from Google Play that violate those policies.”