The SwiftKey app has temporarily disabled the ability to sync on new devices SwiftKey Facebook

SwiftKey, a keyboard application for smartphones that uses artificial intelligence (AI) to predict the content of messages, has been forced to disable a key part of its service after multiple users complained the app was spilling private data.

The application, which is available for both iOS and Android, works for social media messages, emails and phone numbers – however some users have found that after installing SwiftKey on new devices, predictions, numbers and even full email addresses belonging to strangers were already appearing.

This has forced SwiftKey to suspend the ability to sync the application to new devices. In a statement released on 29 July, the firm acknowledged the flaw and claimed to be "working quickly" to resolve the problems.

"This week, a few of our customers noticed unexpected predictions where unfamiliar terms, and in some rare cases emails, appeared when using their mobile phone," it said.

"While this did not pose a security issue for our customers, we have turned off the cloud sync service and are updating our applications to remove email address prediction. During this time, it will not be possible to back up your SwiftKey language model."

The firm maintained the "vast majority" of users will not be affected. It added: "We take users' privacy and security very seriously and are committed to maintaining world-class standards for our community."

German predictive text - despite not speaking German

According to The Telegraph, one user discovered their details had been compromised after being contacted by a stranger who thought the new device they had purchased was previously bought and returned as email addresses, names and addresses were already stored in SwiftKey.

Meanwhile, a separate issue was disclosed by a user on Reddit who complained about being served predictions in German, despite having never used that language before.

"I logged into SwiftKey with Google+ and now I'm getting someone else's German predictions with only English (UK) pack installed," said the commentor.

"I have never typed German in my entire life [...] I also was suggested an email ID in an email field. It's bad enough to lose a trilingual dictionary built over almost 4 years. Now I'm also worrying about someone getting all my suggestions." In response, on the same Reddit thread, SwiftKey responded: "Our team is looking into this as a matter of priority."

SwiftKey launched on Android in 2010 and arrived on the official Apple Store in 2014. On its website, it claims to be featured on over 300 million devices. The UK-based business was purchased by computing giant Microsoft in April 2016 for £173.2m ($250m).