SHANGHAI, China (AP) -- A blood thinner manufactured in China and linked to dozens of deaths in the United States is now safe because of tighter testing and controls, a top American health official said Monday, while warning that all U.S. imports would face closer scrutiny in the future.

The U.S. Food and Drug Administration has linked 81 deaths and hundreds of allergic reactions to a contaminant found in China-made shipments of the drug heparin.

''We have put in place processes that we believe can ensure the safety of the heparin supply within the United States,'' U.S. Health and Human Services secretary Mike Leavitt told The Associated Press in an interview in Shanghai.

He said all exporters of food, drugs and other products must prepare to meet more stringent guidelines of quality and safety, following a raft of product safety problems stemming from lax standards among overseas producers, especially in China.

''We believe the system that we have for ensuring safety is a good one but completely inadequate for the future,'' Leavitt said.

''What you'll see from the United States is a substantial change in our strategy,'' he added, noting Washington's plans to station Food and Drug Administration inspectors in China and other countries.

Leavitt said he was optimistic that American and Chinese officials could soon resolve a dispute over the FDA's investigation into the cause of deaths and reactions linked to heparin.

Washington plans to set up FDA offices in China to help improve product safety following allegations that many of Beijing's exports -- from toys to fish -- are shoddy or dangerous.

China's drug safety agency has accused the U.S. of blocking its own inquiry into the problem by refusing to provide details on victims and specifics about production. Beijing contends that it is too early to conclude that a contaminant found in raw heparin exported to the United States caused the adverse reactions.

A report published Friday said the FDA was concerned that some medical facilities may still have heparin in stock.

Leavitt said that the need to prevent a shortage of heparin, widely used in dialysis and other common medical procedures, required that the FDA find ways to maintain the supply and quality of the drug.

''The FDA is satisfied that that which is coming into the United States is safe,'' he said. ''Testing regimens have been put in place to ensure that.''

Leavitt was due to meet later with China's minister of health to discuss various issues, including a viral outbreak that has killed at least 34 children and sickened thousands.

He said he planned to reiterate a U.S. offer to help China in its fight against the outbreaks of hand, foot and mouth disease.