The Korean operator of Dunkin’ Donuts, BR Korea, issued an official apology Thursday saying it will “thoroughly abide by sanitary standards,” following a video showing donuts baked in unsanitary conditions.

South Korea’s public broadcaster KBS aired on Wednesday a video taken by an anonymous worker this summer showing the inside of the firm’s donut factory in Anyang, Gyeonggi Province.

The footage shows dough stained with orange droplets that are presumed to have fallen from ventilators above. Frying machines were seen covered with black mold-like substances.

According to KBS, the factory in question is responsible for 60 percent of all donuts made locally. Dunkin’ Donuts operates around 600 stores across the country.

In a statement posted on the Dunkin’ Donuts’ Korean website, BR Korea said it was investigating hygiene standards at the factory and how well they were observed.

“We are internally investigating the matter. The Korea Food & Drug Administration also conducted a spot check of the facility Wednesday morning,” read the statement.

It also said it will “come up with internal and external measures” depending on the investigation results and “carry them out as quickly as possible,” as well as doing its ”best to produce and supply safe products under strict hygiene guidelines.”

Share prices of SPC Samlip, the mother company of BR Korea, inched down 1.42 percent on Thursday, amid the negative coverage.