Amid indications that more people may have died or been harmed after being given a brand of the blood thinner heparin, federal drug regulators said Thursday that they had found "potential deficiencies" at a Chinese plant that supplied much of the active ingredient for the drug. Baxter International, which makes the brand of heparin associated with the problems, and buys supplies from the Chinese plant, announced that it was expanding a recall to include virtually all its heparin products. Though Baxter produces much of the heparin used in the United States, regulators said the other major supplier would be able to meet the demand.

The Food and Drug Administration said the number of deaths possibly associated with the drug, made from pig intestines, had risen to 21 from 4. But it cautioned that many of those patients were already seriously ill and that the drug might not have caused their deaths. The FDA emphasized that it had yet to identify the root cause of the problem, and that it had not concluded that the Chinese plant was responsible. The agency also said it was investigating two Chinese wholesalers -- also called consolidators -- that supplied crude heparin to the Chinese plant, Changzhou SPL, as well as those that sold raw ingredients to the consolidators.

The New York Times reported Thursday that at least one of the consolidators received supplies from small, unregulated family workshops that scraped mucous membrane from pig intestines and cooked it, eventually producing a dry substance known as crude heparin. The FDA admitted this month that it had violated its own policy by failing to inspect SPL, located west of Shanghai, before the factory began shipping the heparin ingredient to Baxter in 2004. China’s drug agency also did not inspect the plant.

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