Awkward moment new iPhone X Face ID feature fails during Apple exec's demonstration

Apple's senior vice president has had an awkward moment in front of a large crowd after the iPhone X facial recognition feature failed to launch.

Craig Federighi, was giving a demonstration on the device's Face ID function and explained to the audience that unlocking the phone "was as easy as looking at it and swiping up."

But after staring down at the phone and trying to swipe, it prompted him to enter his passcode.

Apple's senior vice president had an awkward moment when the facial recognition feature failed. Photo: Apple

Mr Federighi laughed before going to the phone's back-up to unlock it and continue with his presentation.

"With iPhone X, your iPhone is locked until you look at it, and it recognises you. Nothing has ever been more simple, natural and effortless," he said earlier.

"We call this Face ID. Face ID is the future of how we unlock our smartphones and protect our sensitive information."

After staring down at the phone and trying to swipe, it prompted him to enter his passcode. Photo: Apple

While some made fun of the mistake suggesting the phone had faults, others pointed out that it might not be the device's fault.

They pointed out that the phone had just been restarted, meaning the user would have had to enter a passcode anyway.

On Tuesday chief executive Tim Cook called the new device "the biggest leap forward" since the first iPhone. ("X" is pronounced 10, not the letter X.)

Apple also unveiled a new iPhone 8 and a larger 8 Plus with considerable upgrades to cameras, displays and speakers.

As expected, the X loses the home button, which revolutionised smartphones when it launched and instead will use facial recognition to unlock the phone.

It is water and dust resistant and will come in space grey and silver. The top model will sell in Australia for $1829.