The strike at the Atsumitec Auto Parts in the city's Nanhai district began on Monday afternoon, after management announced changes to workers' shifts that would cut their overtime hours and increase their workload. The company also refused to provide lunch on Tuesday and Wednesday, making the workers angrier.
Cutbacks are partly the result of to the global economic crisis, but they are especially hard on workers who rely on overtime, as the basic salary is only 1,070 yuan (US$ 160) per month.
About four-fifths of that income is spent on basic daily expenses such as food, accommodation and transport.
Workers want an extra 500 yuan on top of their basic monthly salary.
The average salary for a young migrant worker in the region is about half the average income last year.
In response to the threat of firing 90 frontline comrades, workers said that if that should happen, they would all quit and seek legal redress.
Mainland media have been banned from covering any strikes as the authorities fear more workers in Guangdong Province might follow suit.
In recent weeks, a series of strikes at plants owned by Honda, Toyota and other companies ended in wage hikes.
For the past 30 years, China’s model of development has been based on the exploitation of cheap labour, mostly migrants from the countryside. The country has become wealthy, but most of those responsible for the new wealth have been excluded from sharing it.
Peking University sociologist Lu Huilin urged the authorities to change the country's current development model, because it comes at the expense of the dignity of millions of workers.
The mainland “used a lot of cheap labour to pursue economic growth while ignoring workers' basic human rights and social equity," he said. "Young migrant workers resist the [sweatshop] system by instinct . . . . If you don't change it, problems will emerge in an endless stream."