SHANGHAI (Reuters) - Viral photos and news reports in the United States allegedly showing a moldy ice cream maker at a U.S. outlet of McDonald’s Corp have prompted swift action from the fast-food giant thousands of miles away: in China.

A McDonald's restaurant is pictured in Encinitas, California September 9, 2014. REUTERS/Mike Blake

The firm’s China unit posted a statement late on Wednesday on its Chinese microblog reassuring customers about the safety and cleanliness of its ice cream machines and other food-making tools, responding to reports and pictures swirling online.

The statement, which also appeared at the top of the burger chain’s China website, underlines the sensitivity to potential food safety concerns in China, one of the most important markets for McDonald’s and rival Yum China Holdings.

“We’re paying attention to the information being reposted today online about U.S. ice cream machines,” McDonald’s China said in the statement, adding the firm was investigating the case in the United States.

“In China, ice cream machines used at McDonald’s restaurants are automatically disinfected every day at a set time to ensure food safety.”

There was no similar statement posted prominently on McDonald’s U.S. website on Thursday.

McDonald’s and Yum Brands Inc, the global owner of KFC and Pizza Hut, have been hit before in the country by food safety scares, which can spread rapidly online in China and have an outsized impact on sales.

Media outlets including BuzzFeed, the Huffington Post and Mashable ran reports on Wednesday with photos showing a tray from an ice cream machine full of mold and dirt. The photos had earlier been posted online by a person who said he was an employee at a McDonald’s outlet in Louisiana.

On Thursday, Chinese media outlets picked up on the reports too. Some netizens posted it would put them off eating at the chain, though others defended the firm and pointed to how sensitive foreign brands were to any potential food scares.

“I think (Yum’s) KFC and McDonald’s are scared witless in China,” posted one user on microblog Weibo under the handle ‘Fei Na Xiong An’. “But clearly in terms of cleanliness they’re a lot better than the vast majority of local restaurants.”