Tech giant Apple was launching its iPhone X, or iPhone 10, on Tuesday (Sept 12), when an embarassing glitch occurred.

It happened during a special event held at the Steve Jobs Theatre in Apple Park.

When Apple software chief Craig Federighi went onstage to demonstrate how to use the facial recognition feature, it did not go as planned.

"Unlocking it is as easy as looking at it and swiping up," he had said.

But he failed to unlock the iPhone with his face, and the passcode screen appeared, which meant he had to manually key in a passcode to access the phone, and that the facial recognition feature had in fact failed to recognise his face.

"Ho, ho, ho," Mr Federighi said awkwardly.

He then turned to a backup phone, on which the function worked, sparing Apple any further blushes on its big night.

The facial recognition feature on the iPhone X, created in commemoration of the 10th anniversary of the trendsetting smartphone, is supposed to also recognise faces in the dark, and also changes in hairstyles and facial hair.

The iPhone X also bears a stainless steel chassis with a curved glass back, instead of the aluminium unibody chassis of its predecessors.

The previous horizontal orientation of the rear dual-camera system, is now vertical on the iPhone X.

The phone will be available in Singapore on Nov 3, with prices starting from $1,648 (64GB, without contract) to $1,888 (256GB, without contract).

Pre-orders start from Oct 27.