A concept design for Apple's much-rumoured iOS-powered smartwatch has appeared online, Digital Spy said.

Professional designer Stephen Olmstead posted the illustration on The Verge's forums to offer his take on what the so-called iWatch will look like.

Olmstead predicts that Apple will opt for a minimalist design with a circular screen and Siri as the primary user input.

"My main focus here was to create a watch that... well... looks like a watch and not a rectangular screen bolted onto a watch band," said the designer.

"I'm particularly fond of the thought of using a watch as a remote trigger for the camera on my iPhone - wouldn't that be fun?"

Apple is yet to officially announce the iWatch, but reports suggest the Cupertino firm has a team of around 100 people working on the product.