WASHINGTON (Reuters) -Pharmacy benefit manager Express Scripts sued the U.S. Federal Trade Commission on Tuesday over the regulator's recent drug pricing report, calling the report's conclusion that the prescription middlemen raise drug costs defamatory.

The lawsuit asks a federal judge in St. Louis, Missouri to order the FTC to take the report down and recuse Chair Lina Khan from any actions pertaining to the company, which is owned by Cigna Corp.

The FTC said in the July report that market consolidation has led to PBMs favoring their own affiliated businesses, which creates conflicts of interest that prevent smaller independent pharmacies from staying competitive by steering patients away from them.