USERS of Apple's iMessage service are this morning reporting a problem with the message tool.

The iMessage platform, which runs on iPhones, iPads and Mac devices, sends messages between those devices rather than as text messages, meaning they do not cost anything other than data usage.

However, many users are reporting an outage meaning they are unable to contact friends and colleagues.

When an iMessage works, the message is blue whilst when the message goes as an SMS (text) message, it will be green.

Apple has not commented on the problem, and not all users are affected.