The Iowa Republican’s letter to the company cites findings from a series of Wall Street Journal articles.

The Wall Street Journal says the U.S. Justice Department in recent months has launched an investigation into UnitedHealth Group’s billing practices to see if the company fraudulently used diagnosis data to trigger extra Medicare Advantage payments.

The probe is analyzing the company’s practice of frequently logging diagnoses that trigger larger payments to its Medicare Advantage plans, according to a report.

D: Noon on Feb. 21The Department of Justice is probing UnitedHealth Group's billing practices in Medicare Advantage, according to a report from the Wall Street Journal. | The Department of Justice is probing UnitedHealth Group's billing practices in Medicare Advantage,

UnitedHealth Group (UNH) is under fire over its Medicare billing practices. The Wall Street Journal reported Friday that the U.S. Department of Justice (DOJ) has launched a civil fraud investigation into how the company records diagnoses that lead to extra payments for its Medicare Advantage plans.

The new civil fraud investigation is examining UnitedHealth's practices for recording diagnoses that trigger extra payments to its Medicare Advantage plans, including at physician groups the insurance giant owns, the report added. DoJ and UnitedHealth did not immediately respond to a Reuters request for comment.

The Iowa Republican’s letter to the company cites findings from a series of Wall Street Journal articles.