China has been experiencing a surge in labour unrest at foreign-owned factories as a new generation of mostly migrant workers agitates for a greater share of the country's growing wealth.

Strikes have been reported this week at a Taiwanese-owned sporting goods supplier in Jiangxi province, and at Japanese sewing machine maker Brother Industries in Xian -- both far from China's wealthier regions near Hong Kong and Shanghai.

The burst of reported strikes is a worry for China's ruling Communist Party, which has long discouraged independent worker action and punished protesters.

While Beijing has made vows of better incomes for workers and farmers a cornerstone of policy, local officials are often focused on attracting investors with cheap, trouble-free labour to fuel China's export boom.

On Friday, about 500 workers gathered on the road outside Honda Lock, which makes locks for Honda cars in China in the city of Zhongshan near Macau, and refused to start work.

Their demands included higher pay, as well as the right to choose their own representation instead of having to use official state-sanctioned labour unions.

Management representatives using loud-hailers warned of "serious consequences" if the strike continued and asked people to sign a paper agreeing to a 100 yuan ($15) raise per month, far less than workers were asking.

About 50 riot police blocked one end of the street at one point, but later gave way to let workers leave the area after management told them to go home and return in the afternoon to negotiate. Few workers heeded that call, in a protest that was largely light-hearted.

DISPUTES SPREAD

"The workers feel that their wages have been held too low for too long. Once you take away food and other costs, most of them are saving maybe 800 or 900 yuan ($117-$132) a month," said Zhang Jun, an independent labour activist from the coastal city of Yantai.

"Young workers these days need to save up money for housing and to get married and have children, and for them that amount just isn't enough. As well, they see the vehicle makers doing such thriving business, and they feel their contribution isn't reflected in their wages and treatment."

Confrontation at Honda follows a growing number of labour disputes in China that started in the affluent Pearl Delta area of Guangdong but have since shown signs of spreading to other areas.

Workers at the Honda Lock factory have been striking since Wednesday, the third factory supplying Japan's No.2 automaker to go on strike in the past month.

Honda China said on Friday that two of its car-making plants that were idled by the series of disputes were producing again on Friday. It added the lock factory strike was having no impact on operations for now, but it was not clear if work would continue over the weekend.

All of the problems reported so far have occurred at foreign-run factories, prompting at least one company, Taiwan's Hon Hai, to say it is looking for other locations to shift some of its production.

Labour costs in general still only make up a small portion of most companies' costs in China, usually around 5 percent.

Most disputes centre on workers resentful of large income gaps, higher living costs and long hours with little rest, and employers trying to rein in rising costs as labour pools shrink.

Resolution of the disputes has resulted in sizable pay increases, including a 66 percent raise for workers.