WASHINGTON - A federal strike force has charged 91 people, including doctors and nurses, in seven cities with Medicare fraud schemes involving $429 million in false billings.

At a news conference, Attorney General Eric Holder says the case reveals an alarming trend of criminal attempts to steal billions of taxpayer dollars for personal gain. Holder called Thursday's action against Medicare fraud one of the largest of its kind.

Health and Human Services Secretary Kathleen Sebelius says that that in addition to the newly announced charges, her agency used new authority under the federal health care law to stop future payments to many of the health care providers suspected of fraud.

The law enforcement effort targeted fraudulent Medicare schemes in Baton Rouge, La.; Brooklyn, N.Y.; Chicago; Dallas; Houston; Los Angeles and Miami.