Samsung has acknowledged labor abuses at its factories in China and vowed to immediately overhaul all of its suppliers in the country.

The company was responding to China Labor Watch's investigation of Samsung's eight plants and suppliers in China. The United States-based organization alleged that widespread abuses such as excessive overtime, exhausting working conditions that require employees to stand while working and cases of forced overtime without pay, were found in the factories.

According to a statement on Samsung's website, the company sent an investigation team from its headquarters in South Korea in August to look into working conditions at some of its plants and suppliers in China.

The statement suggested that the company paid special attention to HEG Electronics in Huizhou, which was accused by China Labor Watch of using child workers.

The statement said HEG Electronics did not employ child workers and Samsung has "zero tolerance" for the hiring of underage workers, "but we found some management problems and hidden work safety troubles in the company".

Samsung said the audit found that some employees at HEG Electronics worked more than nine hours of overtime a week.

Chinese law allows 40 regular hours plus nine hours of overtime a week.

According to China Labor Watch's report, overtime for some employees reached or exceeded 100 hours per month, with some employees having only one day off a month.

Fu Yongkai, deputy general manager for HEG Electronics, admitted that some employees worked more overtime than legally permitted.

"I do not know how the US organization calculated the excessive working hours, but as far as I know, we did not make workers take such excessive overtime work," he said.

"We will adjust working conditions according to Chinese laws and Samsung's own labor standards as to what Samsung has required us to do so."

Fu also admitted that they made workers stand for long periods during work, but he added: "We allow workers to take a 10-minute break between every two hours of work."

Fu said they've never forced employees to work overtime without pay.

Fu's company employs around 3,000 workers and it mainly produces phone products for Samsung.

Fu said at his company, workers earn a basic salary of 1,150 yuan ($180) a month, higher than the Huizhou's minimum wage standard of 950 yuan.

Fu said workers are paid their basic salary plus additional money earned through overtime.

Repeated calls to the information office of Huizhou government went unanswered on Wednesday afternoon.

China Labor Watch's report also said that while Samsung suppliers Tianjin Intops Co and Tianjin Chaarmtech Electronics Co complied with local minimum wage laws - workers were paid the base monthly salary of 1,310 yuan - the pay was so low that many workers felt compelled to work overtime.

The organization said Samsung also failed to provide an avenue through which workers could make complaints.

Samsung said it would re-evaluate its labor practices in China.

"We frequently review our manufacturing facilities regarding overtime work. We will re-evaluate working hour practices," spokesman James Chung said.

"When new production lines are completed or new products are launched, high demand has led to overtime work."

Samsung said it will audit working conditions at around 250 Chinese companies in its supply chain by the end of the year.

Starting next year, the company will invite a third-party organization to carry out a regular audit of working conditions at all of its suppliers in China.

It vowed to terminate contracts if any labor abuses or violations of its policies are found.

A flurry of worker suicides at Foxconn Technology Group, Apple's largest supplier, drew attention to conditions faced by workers in China who manufacture iPhones and other devices.

Agencies contributed to this story.

chenxin1@chinadaily.com.cn