The nation’s biggest provider of pharmaceuticals to long-term care facilities is under investigation for possibly steering some Medicare beneficiaries to enroll in certain Medicare prescription drug plans, according to the United States Attorney’s Office, District of Massachusetts.

Omnicare Inc., based in Covington, KY, has said it will cooperate with the government agencies investigating the company’s programs related to the implementation of Medicare Part D. It maintains it is in full compliance “with all applicable laws and regulations with respect to these matters,” according to a company statement.

Under review are documents from a separate lawsuit Omnicare filed against UnitedHealth Group for alleged illegal negotiations that left Omnicare with a lower reimbursement rate. UnitedHealth Group in September received a subpoena from the Department of Justice requesting information about Omnicare.