A facility in China run by a US supplier produced the active ingredient in a blood thinner currently under investigation in the US following reports of hundreds of allergic reactions and four deaths among its users, the Wall Street Journal reported, citing the US Food and Drug Administration (FDA). The FDA and Baxter International, the maker of the blood thinner, said it was unclear whether the product from the Chinese facility is tied to reactions that occurred in some patients who took heparin, an anticoagulant made by Baxter. The FDA has not inspected the Chinese facility, though it could do so through a cooperation agreement with China’s State Food and Drug Administration. Baxter declined to name the supplier of the active ingredient. The news is likely to spark inquiries from Congress and consumer advocates already voicing their concerns about the safety of Chinese products. Baxter has temporarily suspended production of heparin.