NEW YORK (AP) — The Justice Department is suing to block UnitedHealth Group's $3.3 billion purchase of Amedisys, citing concerns the combination would hinder access to home health and hospice services in the U.S.

The antitrust complaint was filed in Maryland federal court Tuesday. In a statement, U.S. Attorney General Merrick Garland said the government is challenging UnitedHealth and Amedisys' proposed merger because "patients and their families experiencing some of the most difficult moments of their lives deserve affordable, high quality care options."

The suit follows UnitedHealth's acquisition of LHC Group Inc., another home health and hospice provider. Since that transaction's completion last year, the Justice Department said, UnitedHealth and Amedisys have emerged as the two largest providers of home health and hospice care in the country.

The department argues that eliminating competition between UnitedHealth and Amedisys "would harm patients who receive home health and hospice services, insurers who contract for home health services, and nurses who provide home health and hospice services."

Four states' attorneys general — from Maryland, Illinois, New Jersey and New York — are joining the Justice Department in the antitrust complaint.

UnitedHealth is seeking to add Amedisys to Optum, its subsidiary that provides care as well as pharmacy and technology services. Optum said Tuesday the acquisition "would be pro-competitive and further innovation." It said it plans to "vigorously defend (itself) against the DOJ's overreaching interpretation of the antitrust laws."

Louisiana-based Amedisys added that it also remains committed to the deal, which it believes "will create more opportunities to deliver quality, compassionate and value-based care to patients and their families."

Beyond its Optum unit, UnitedHealth Group also runs one of the nation's largest health insurers, UnitedHealthcare. Last month, the Minnesota-based healthcare giant reported third-quarter net income of $6.06 billion on revenue of $100.82 billion.