A customer holds a McDonald's ice cream in front of its Nanjing East Road store in Shanghai, July 27, 2017. [Photo/VCG]

Shanghai Municipal Food and Drug Administration raided four McDonald's restaurants in the city on Thursday and didn't find food safety problems, the Information Office of Shanghai Municipal Government said late Thursday.

During the raids, the restaurants' purchase records, the employees' operating process and the sanitation of the kitchen were some of the steps inspected.

The inspection came after a former employee of a restaurant of the US fast food behemoth in Louisiana posted pictures on social media of a greasy part of a machine that he claimed produced homemade ice cream in the restaurant, which triggered online discussion in China.

Zhang Qi, restaurant manager of a McDonald's store on Minhang district's Hechuan Road, said the ice cream machine undergoes disinfection automatically for three hours before daybreak on a daily basis and is opened every 14 days for maintenance and cleaning.

The Shanghai FDA also summoned senior officials from the Shanghai-based China branch of the industry giant for talks on Thursday and urged it to fulfill its non-delegable duty as a huge fast food chain and be 100 percent meticulous about food safety details.

McDonald's China said in a statement on Thursday that the US branch had verified the machine part in the pictures was a tray that carries dripping lubricant inside the machine when it is running, and the part has no contact with food.

"This issue has nothing to do with our Chinese restaurants," read the statement issued on the company's official Sina Weibo.

"We earnestly request the public to trust us that we have rigorous standards for food safety, which is always our priority," it added.

zhouwenting@chinadaily.com.cn