Thirty-five restaurants in China have been accused of illegally using opium poppies as a seasoning in their food, officials reportedly said Friday. The China Food and Drug Administration said five restaurants are being prosecuted while an investigation is underway into 30 others.

According to reports, cases of ground poppy powder, which contains low amounts of opiates such as morphine and codeine, being sprinkled into food such as soup and seafood are not new in China. Such cases have emerged in China since 2004, when the southwestern Guizhou province shut down 215 restaurants. The use of poppy powder as a food additive is banned in China, BBC reported.

The popular Huda Restaurant chain in Beijing is reportedly one of the businesses affected by the latest crackdown. General Manager Hu Ling confirmed that the company was under investigation, and said that it may have accidently bought seasoning contaminated with opiates, BBC reported.

China has faced several food scandals in recent years. In 2014, a Shanghai-based supplier was found to have sold unsanitary and expired chicken meat to food chains including KFC, Starbucks and McDonald's.