A Chinese factory that supplies much of the active ingredient for Baxter’s Heparin, which has been linked to hundreds of adverse reactions and four deaths in the US, isn’t certified by China’s drug regulators to make pharmaceutical products, The New York Times reports. As a result, China’s drug agency never inspected the plant run by Changzhou SPL. Earlier this week, the FDA acknowledged it never inspected the plant either.

Although Chinese drug regulators have said that all ingredient producers are required to obtain certification, some chemical companies don’t fall under the Chinese drug agency’s jurisdiction. The Changzhou plant hasn’t been accused of providing a harmful product. But in response to questions, Scientific Protein, which is a majority owner of the plant, issued a statement to the Times confirming its Chinese plant was unlicensed, although it insisted its raw ingredients come from a licensed supplier.

The statement added that an “independent private US validation company” found the plant was in compliance with good manufacturing practices. And a spokeswoman for Baxter, which buys heparin’s active ingredient from Scientific Protein, told the Times that it inspected the Changzhou plant less than six months ago. A spokesman for China’s State Food and Drug Administration, Shen Chen, told the paper that “as far as we know, it is not a drug manufacturer - it is a producer of chemical ingredients.”

But Eric Langer, managing partner of BioPlan Associates, which prepares and publishes reports on the biopharmaceutical and biotechnology industry, said he found it hard to believe that a company exporting the heparin ingredient would not be licensed by Chinese drug regulators. “Being able to produce a pharmaceutical or a biologic in the U.S. or anywhere without having regulatory oversight really doesn’t happen,” he tells the Times. “I find it surprising from a regulatory perspective, and I find it surprising from a business perspective.”

An FDA spokeswoman, Karen Riley, tells the paper the aency would be visiting the Changzhou plant soon, but couldn’t be more specific. Earlier in the week she described her agency’s failure to inspect the plant as a “glitch.”

Problems with Baxter’s heparin were first noticed late last year when four children undergoing dialysis in Missouri had severe allergic reactions minutes after being injected with the drug. A Baxter spokeswoman, Erin Gardiner, defended Scientific Protein, saying it had been making the heparin ingredient for more than 30 years. “They have been a good supplier,” she tells the Times.

She adds that tests performed by Baxter detected unspecified differences between some lots of the ingredient, but didn’t say whether the lots had come from China or from the Wisconsin plant, which Scientific Protein also owns. Those differences didn’t turned up in routine testing Baxter performs on active ingredients, but she tells the Times that Baxter used “advanced testing techniques” to find the differences. She added that it was unclear whether the finding was significant.