They all had ‘20+ Samsung’ printed on the surface, and 836 said made in China while the rest had no indication of origin.

Hoang Dai Nghia, head of the Hanoi Market Surveillance Department’s Team 1, said the power bank packages that did not carry the Samsung name, and so if the inspectors had not been thorough they might not have noticed the illegal use of the Samsung trademark.

Market authorities warned that using batteries and power banks without clear origins or of dubious quality could result in fires and explosions.