(Reuters) - The Justice Department and three U.S. states filed a lawsuit on Tuesday to block UnitedHealth Group's ( UNH ) $3.3 billion purchase of Amedisys Inc ( AMED ) over concern the deal would harm competition in the market for home health services, the department said.

"Eliminating the competition between UnitedHealth ( UNH ) and Amedisys ( AMED ) 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," the department said in a statement.