Chinese authorities detained or interrogated more than a dozen labor activists in a southern manufacturing hub this week, a sweep that underscores Beijing’s growing anxiety over worker unrest…The activists, mainly based in the cities of Guangzhou and Foshan, were rounded up by police for questioning Thursday, according to some of the activists and their associates. They said as many as 19 people were taken in…at least 10 people remained out of contact as of Saturday evening, including three activists who have been placed under criminal detention…

It wasn’t clear what prompted the sweep, though…have increasingly clamped down on industrial unrest that has swelled over the past year, amid an economic slowdown that has led to a rise in layoffs and wage disputes…Scholars say the crackdown appeared to target activists who focus on organizing workers involved in labor disputes and advising them on how to collectively negotiate over unpaid wages and other grievances.

…One of the activists under criminal detention is Zeng Feiyang, founder of the Guangdong Panyu Migrant Workers Center, which has been assisting workers in collective negotiations, including in a recent dispute between sanitation workers and their employment agency…