health insurance system.

Data being released for the first time by the government on Wednesday shows that hospitals charge Medicare wildly differing amounts — sometimes 10 to 20 times what Medicare typically reimburses — for the same procedure, raising questions about how hospitals determine prices and why they differ so widely.

The data for 3,300 hospitals, released by the federal Centers for Medicare and Medicaid Services, shows wide variations not only regionally but among hospitals in the same area or city.

Government officials said that some of the variation might reflect the fact that some patients were sicker or required longer hospitalization.

Nonetheless, the data is likely to intensify a long debate over the methods that hospitals use to determine their charges.

Medicare does not actually pay the amount a hospital charges but instead uses a system of standardized payments to reimburse hospitals for treating specific conditions. Private insurers do not pay the full charge either, but negotiate payments with hospitals for specific treatments. Since many patients are covered by Medicare or have private insurance, they are not directly affected by what hospitals charge.

Experts say it is likely that the people who can afford it least — those with little or no insurance — are getting hit with extremely high hospitals bills that may bear little connection to the cost of treatment.

“If you’re uninsured, they’re going to ask you to pay,” said Gerard Anderson, the director of the Johns Hopkins Center for Hospital Finance and Management.

The debate over medical costs is growing louder, spurred partly by President Obama’s overhaul of the health insurance system.

Hospitals, in particular, have come under scrutiny for charges that are widely viewed as difficult to comprehend, even for experts. “Our goal is to make this information more transparent,” Jonathan Blum, the director of the agency’s Center for Medicare, said in an interview.