Shanghai Husi Food, which is at the centre of a food scandal in China, was sued by a former employee in 2013 for allegedly forcing him to do unethical work.

However, the company won the case filed by former quality control officer, Wang Donglai, Reuters reported.

Wang, who worked at Shanghai Husi Food from 2007 to 2013, earlier filed a lawsuit, alleging that the meat processor had forced him to do "unethical work" that violated food safety laws.

At a hearing in October, Wang alleged he was forced to illegally forge meat production dates at the plant in violation of food safety laws and consumer interests, the news agency reported, citing court documents. He repeatedly urged his employer to change the practice, but the plea was ignored.

In the lawsuit, Wang also sought around 38,000 yuan ($6,100) from the company for damage to his health due to alleged exposure to chlorine used as cleaning agent by the company. Besides, he alleged that he was forced to work overtime at the firm.

Wang lost the case at the Shanghai Jiading District Court in January, as the court said it could find evidence to substantiate his allegations.

"I believe Husi has sufficiently learned its lesson (from the current scandal) and if it wants to survive it certainly needs to improve its standards," Xia Yugang, a lawyer who represented Shanghai Husi in the case, told Reuters.

The Chinese local media earlier reported that Shanghai Husi Food, owned by US-based OSI Group, sold chicken and beef past their expiry dates to international food chains including McDonald's, KFC and Pizza Hut.

Subsequently, Shanghai's Food and Drug Administration conducted a raid at the firm's facilities and seized more than 5,000 boxes of expired meat. In addition, police detained five employees at the firm, including its quality manager.

Nine companies including KFC, McDonald's, Burger King and Papa John's have used products from Shanghai Husi. Following the outbreak of the scandal, the companies apologised to Chinese customers and said they were taking the products concerned off the shelves.