Google has said it will update its new Pixel 4 phones to prevent them being unlocked using the sleeping faces of their owners.

The phones, which are not yet in shops, are the first from Google to include a secure face unlock feature, in place of the fingerprint sensor used on previous iterations. The feature is also used to confirm payments and sign in to apps.

Unlike the similar feature on iPhones, FaceID, the Pixel face unlock does not require the user to be looking at the phone – or even to have their eyes open.

The operating system warns users that “your phone can be unlocked by someone else if it’s held up to your face, even if your eyes are closed”.

Google has announced an update that will offer a more secure option. “We’ve been working on an option for users to require their eyes to be open to unlock the phone, which will be delivered in a software update in the coming months,” it told technology website The Verge.

“In the meantime, if any Pixel 4 users are concerned that someone may take their phone and try to unlock it while their eyes are closed, they can activate a security feature that requires a pin, pattern or password for the next unlock.”

Google’s initial decision was based on a tradeoff between speed and security, with the company focusing more on speed than Apple had when it launched its competing system in 2017 alongside the iPhone X.

Apple pointed out that FaceID required user attention to work, preventing what one reporter called the “girlfriend nap” attack, when a suspicious partner could try to unlock the phone of their sleeping partner.