Workers in China are being hooked up with brain-reading devices that feed information about their moods to their employers, raising concerns about the privacy of people’s most basic emotions.

Electronic sensors that fit into hats and helmets are being used in China on an “unprecedented” scale to read employees’ emotions, the South China Morning Post reports, in what firms say is part of a drive to increase efficiency and productivity,

But the efforts to tap into the data is sparking concerns that powerful companies are reading the minds of their employees, with one Chinese psychology professor warning that the systems could represent a "whole new level" of privacy abuse.

Although details about how the technology works are not clear, reports suggest devices use lightweight sensors and artificial intelligence algorithms to monitor brainwaves and detect spikes in emotions such as rage, anxiety and depression. They can be concealed in safety helmets or uniform hats, and stream data to computers accessed by employers.

The Post reports that the technology is government-backed and is known to be used in the electronic equipment, electric power supply and telecommunications industries, plus in the military in China.