A device that can read people's minds by detecting their brainwaves has been developed in a breakthrough that could eventually enable people with "locked-in syndrome" to communicate.

The system was only partially effective with a 90 per cent success rate when trying to recognise numbers from zero to nine and a 61 per cent rate for single syllables in Japanese, the researchers said.

But, nonetheless, a statement about the research issued by the Toyohashi University of Technology in Japan said it showed that an effective device to read people's thoughts and relay them to others was possible in the "near future".

They even suggested an "easily operated" device with a smartphone app could be ready in just five years.

An electroencephalogram (EEG) was used to monitor people's brain waves while they spoke.

The brain waves were then matched to the syllables and numbers using "machine learning", a process used to develop artificial intelligence.