European trade union leaders, including three UK unions, have called on the European commission to open an investigation into Amazon’s “potentially illegal” effort to spy on workers for union activities.

The heads of some of Europe’s biggest unions, representing more than 12 million workers, wrote to the commission to demand an investigation into Amazon’s work practices across the continent. The move comes after the US tech firm advertised jobs for which part of the description was investigating the threat of organised labour against the company.