While many university students enjoy carefree lives, Crystal Chow Ching and Bibianna Yip Cho-yan wage war on rogue businesses, hoping to help thousands of exploited labourers on the mainland. Working with Sacom - Students and Scholars Against Corporate Misbehaviour - and other student activists, the two secretly visited a factory in Dongguan which is registered in Hong Kong. They released a controversial 29-page report earlier this month, accusing the company of breaching various aspects of the labour law. The detailed report, which caused an uproar on the mainland, claimed working conditions there were unsafe which led to frequent accidents and unreasonable deductions from the workers' pay. 'We went there in small groups of six at a time to avoid drawing attention,' said Ms Chow, 21, the vice-president of the Chinese University of Hong Kong's student union. 'The factory occupied a large area - larger than any shopping mall in Hong Kong. The whole area stank. It was heavily guarded and we could only peek through fences to see inside.' The students said the air was so polluted the tissue Ms Yip used to wipe her face turned black. 'Since we could not go into the factory, we waited at the bus station and in other places where workers usually hang out after work. Most of them refused to talk to us as they were afraid of losing their jobs,' added Ms Yip, the president of Hong Kong Baptist University's student union. The students said the few brave people who did dare to talk highlighted their dire circumstances. 'They told us there was an industrial accident almost every month. The fork lift trucks - which operate in a narrow and dark environment - always bump into people. In some cases people have been killed,' Ms Yip said. What was worse, they said, was that every time there was an accident the workers and supervisors were fined a few hundred dollars from their salaries which ranged from HK$1,300 to HK$1,500. In some instances, even the person who was injured was fined. 'They work 363 days a year, with only two holidays during the Lunar New Year. They are not allowed to discuss salaries, nor do they know why their pay is cut,' said Ms Chow. This was not the first time Ms Yip had witnessed injustice on the mainland. In 2006, she accompanied her school teacher to the State Letters and Complaints Bureau in Beijing. The office deals with people's complaints against local officials. 'I saw petitioners, who came from remote provinces, were intercepted and beaten up before they even set foot in the office,' she said. 'The officers they intended to complain about were tipped off and sent people to stop them. 'A middle-aged woman from Shandong wept as she told me her son had been injured in a car crash. When they sought compensation, her son was beaten to death.' Now Ms Yip is determined to devote herself to campaigning against social injustice. But neither Ms Chow nor Ms Yip are pleased with their work. 'It is just the tip of an iceberg. There are many more things we need to do,' said Ms Yip, adding she hoped Hongkongers would be more aware when they purchased any goods. Sacom Activist group Sacom first gained public attention soon after it was established in 2005. It revealed several companies making Disney products in Guangdong were exploiting workers by not paying minimum wages and overtime and not providing paid leave. Their accusations prompted Walt Disney Company to investigate and force its product manufacturers to pay the overdue wages.