Labour rights activists received lighter than expected sentences in trials in the southern Chinese province of Guangdong on Monday, as workers in the country’s manufacturing and export powerhouse contend with shifting political winds.

Activists affiliated with the Guangdong Panyu Migrant Workers’ Centre, which mediated with factories on behalf of striking workers, faced charges of “gathering a crowd to disturb social order” and embezzlement after being rounded up late last year.

They received suspended jail sentences of one to three years, meaning they are in effect free but on probation.

Their trials follow renewed scrutiny over organised workers’ representation outside the Communist party, after several years of tightening labour markets during which such organisations were tolerated as a useful civic pressure valve.

They also reflect gathering storm clouds for activists of all stripes, from lawyers to religious groups to prominent ethnic minorities, as an erosion of civic freedoms intensifies under President Xi Jinping.

“These groups were doing the job the official trade union should be doing — organising workers, electing representatives and engaging in collective bargaining with their employers,” said Keegan Elmer, a researcher with Hong Kong-based workers’ rights organisation China Labour Bulletin, ahead of the Monday trial of Zhu Xiaomei, one of the defendants who was freed on bail to take care of her infant.

Ms Zhu and colleague Tang Huanxing received prison sentences of 18 months, deferred for two years. Activist Zeng Feiyang was sentenced to three years imprisonment, deferred for four years. A fourth, veteran activist Meng Han, has been detained for months and was not tried on Monday.

Suspended sentences are often commuted if the person stays out of trouble but for activists they serve as a constant reminder of the risks of further public action.

For the first several decades of Communist rule in China, advocacy of workers’ rights outside of the party-sponsored union was severely punished. But as migrant workers flooded into export-oriented factories along the coast, clandestine labour rights organisations slowly took hold. In the middle of the last decade, as rapidly rising salaries priced out Guangdong’s 1980s-era factories, labour organisations were tolerated as a part of the region’s efforts to rise up the manufacturing value chain.

The tide began to turn under Wang Yang, previously party chief of Guangdong and now vice-premier. Mr Wang began his tenure apparently open to social reforms including resolving land rights disputes and strengthening workers’ claims for severance, salary and injury payments. But by the end of his tenure in early 2013 the province’s freewheeling media were under increasing restraint and a number of active labour groups in the border city of Shenzhen had been shut down.

The Panyu centre appears to have attracted government ire following its role in a shoe factory strike in late 2014.