Apple has pulled an iPhone application which simulated shaking a baby until it fell asleep. But the firm hasn’t given a clear explanation as to how it was approved in the first place.

The application was produced by third-party firm Sikalosoft and approved for sale through the App store section of the iTunes store. Costing 99c to download, the app was promoted with the line “See how long you can endure his or her adorable cries before you just have to find a way to quiet the baby down!”

Players were presented with a drawing of a child and could then shake the phone until the child’s eyes were covered with red crosses.

As you’d imagine, news of the app caused outrage. Jennipher Dickens, a spokeswoman for the Sarah Jane Brain Project and a mother of child left brain damaged after being shaken, said “Words do not even adequately describe how much [the app] disheartens me.”

Sikalosoft isn’t commenting on the app. Apple has confirmed it went on sale on Monday and was withdrawn yesterday, but hasn’t answered any other questions, including how it got approval or how many copies were sold.

It’s the latest in a long string of confusing decisions by Apple over its vetting process, which can take several weeks. The firm has rejected apps including an official South Park clips app (despite the same content being available on iTunes), an internet radio station app which had been approved three times in previous editions, an app allowing users to download podcasts wirelessly to the iPhone, and a movie listing service.

However, it has approved a Google voice search app (which contravenes a ban on using the phone’s sensor which smaller firms have had to follow), an app turning the iPhone into a wireless modem (which breaches the service agreement US users have with AT&T), and a screensaver retailing at $999.