Thousands of workers at a plant in eastern China owned by South Korea's LG Group have returned to work after the firm doubled bonuses to end a three-day strike, a government official said Thursday.

The strike was the latest in a series of work stoppages that have hit China since November, as employees protest over low salaries, wage cuts and poor conditions amid company cutbacks due to the global economic slowdown.

The workers ended the strike at the plant in Nanjing city after the firm raised year-end bonuses to two months' salary from one, said an official of the government-run development zone where the factory is located.

"The workers have started working already. They have accepted the result (of negotiations), otherwise they would not have gone back to work," the official, who declined to be named, told AFP.

Initially, 600 workers walked off the job at the plant on Monday, but the number swelled to more than 2,000 over the course of the strike, the official Xinhua news agency reported.

Workers had complained South Korean employees of the factory, which makes screens for electronic products, received higher bonuses.

The workers receive an average monthly salary of 1,400 yuan ($220), Xinhua said.

Labour activists say authorities in China appear to be more sympathetic to grievances against factories funded by foreign companies or overseas Chinese investors from Hong Kong and Taiwan than domestically-owned plants.

The issue of year-end bonuses has also triggered other strikes in China.

In the southern city of Guangzhou, workers at a Japanese-invested auto parts factory went on strike Tuesday to protest against a bonus cut, the New York-based rights group China Labor Watch said in a statement.

Workers at a factory owned by Ahresty Corp, which supplies components to Japanese auto makers such as Honda and Toyota, complained bonuses had been cut even as working hours increased.

A factory official declined to comment when reached by AFP.

Separately, in a sign that authorities are trying to address worker grievances, police in the southern boomtown Shenzhen arrested nine bosses for failing to pay wages to employees ahead of the end of the year, Xinhua said.

The nine employers owe over eight million yuan to more than 780 workers.

Migrant workers, who provide the labour for factories in the nation's manufacturing hubs, typically seek unpaid wages before returning home for the Chinese New Year, which falls in January.