Hackers are able to work out your online passwords just from the sound of your keystrokes, a new study has revealed.

The latest cyber threat involves criminals using a mobile phone to eavesdrop on their victim's keyboard strokes.

In tests researchers were able to detect what was being typed with remarkable accuracy using just a smartphone.

It could be a major threat to people who use laptop computers in public places like coffee shops, libraries and on public transport.

Cybersecurity experts from Southern Methodist University in Texas found that sound waves produced when we type on a computer keyboard can successfully be picked up by a smartphone.

The acoustic signals intercepted by the phone can then be processed, allowing a skilled hacker to decipher which keys were struck and what they were typing.

The researchers were able to decode much of what was being typed using common keyboards and smartphones - even in a noisy conference room where others were typing and talking.

Study co-author Professor Eric Larson said: "We were able to pick up what people are typing at a 41 percent word accuracy rate. And we can extend that out - above 41 percent - if we look at, say, the top 10 words of what we think it might be."

The study was published in science journal Interactive, Mobile, Wearable and Ubiquitous Technologies.