Until now, mobile phone motion sensors were capable of detecting only repetitive movements such as walking or running.

The KDDI system, is able to detect more complex behaviour by using analytical software - held on a server back at base - to match patterns of common movements.

For example, the KDDI mobile phone strapped to a cleaning worker's waist can tell the difference between actions performed such as scrubbing, sweeping, walking an even emptying a rubbish bin. The aim of the new system, according to KDDI, is to enable employees to work more efficiently and managers to easily evaluate their employees' performance while away from the office.

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"This is treating people like machines, like so many cattle to be monitored and watched over," Kazuo Hizumi, a leading human rights lawyer, told BBC News.