WASHINGTON—The Justice Department said that it has recently charged more than 400 people, including 56 doctors, with committing health-care fraud that generated $1.3 billion in false billings.

“Too many trusted medical professionals like doctors, nurses and pharmacists have chosen to violate their oaths and put greed ahead of their patients,” Attorney General Jeff Sessions said on Thursday at a news conference where he was joined by other top U.S. law-enforcement officials.

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