As part of a five-month investigation, Interpol, the world’s largest international police organization, seized more than 16 million counterfeit tuberculosis, malaria and HIV pills in Southeast Asia, Bloomberg reports.

Under Operation Storm, the production of fake drugs was investigated across China, Laos, Myanmar, Singapore and Cambodia. More than $6.65 million of counterfeit medicine was seized, and 27 people were arrested.

Last year, the Organization for Economic Cooperation and Development reported that Asia is the world’s largest producer of counterfeit medicines, making up 40 percent of the 1,047 arrests related to fake drugs worldwide that same year.

According to the World Health Organization (WHO), 30 percent of all medication in developing countries is counterfeit, in contrast to 1 percent in developed nations.