Samsung investigates child labour claims at Chinese mobile phone factory

As well as child labour, it is claimed HEG Electronics enforces compulsory overtime of three to five hours per day beyond the normal eight-hour production line shift. Workers on HEG’s 11-hour night shift are given only a 40-minute break for meals, China Labor Watch said, alleging that the firm had "slack internal supervision mechanisms".

"Based on the results of this CLW investigation of Samsung's supplier factory, it can be determined that working conditions at HEG are well below those general conditions in Apple's supplier factories," said China Labour Watch.

The group has previously attacked conditions in Apple's supply chain. In December it highlighted an explosion at an iPad parts factory that allegedly injured 61 workers.

The negative publicity surrounding such incidents has led Apple to publish the results of its supplier inspections, which have also revealed the use of child labour.

"We think the use of underage labour is abhorrent," Apple chief executive Tim Cook said earlier this year. "It's extremely rare in our supply chain, but our top priority is to eliminate it totally.”