A federal inquiry has been opened into Google's efforts to collect health data on millions of Americans through its "Project Nightingale" program.
The Department of Health and Human Services' Office for Civil Rights opened the inquiry on Tuesday, The Wall Street Journal reported.
The office "will seek to learn more information about this mass collection of individuals' medical records to ensure that [the Health Insurance Portability and Accountability Act of 1996 or HIPAA] protections were fully implemented," office director Roger Severino said in a statement to the publication.
The Department of Health and Human Services did not respond to CNN Business' request for comment.
The data collection is being done through a new partnership between Google and Ascension, one of the country's largest nonprofit and Catholic health systems. The two companies confirmed they were working together to analyze patient data and give health care providers new insights and suggestions for patient care. The Wall Street Journal was the first to report on the project on Monday.
The partnership between Google and Ascension will integrate Ascension's different areas of health data in the cloud. Google said in a blog post on Monday that the project was a "business arrangement to help a provider with the latest technology, similar to the work we do with dozens of other healthcare providers."
The Journal reported at least 150 Google employees had access to patient data but Google said it's adhering to regulatory standards, such as HIPAA. Google said Ascension's data "cannot be used for any other purpose than for providing these services we're offering under the agreement, and patient data cannot and will not be combined with any Google consumer data."
Shortly after the Journal's report was published, both companies put out statements.
Google acknowledged the sensitive nature of patient health data. Ascension, which is based in St. Louis, has 2,600 facilities in roughly two dozen states. It said its partnership with Google followed the law. But the Journal reported some Ascension employees questioned how Google is sharing and collecting patient data.
This isn't the first time Google has faced scrutiny for its handling of user data.
Google paid a record $170 million penalty to the Federal Trade Commission to settle accusations that YouTube broke the law when it knowingly tracked and sold ads targeted to children.
Google's push into health care comes amid growing interest in the space from tech companies, such as Apple, Amazon and Microsoft. All three companies have launched initiatives to modernize the US health care system in recent years.