FedEx and UPS say they are targets of a Drug Enforcement Administration (DEA) investigation into online pharmacy shipments, the Orlando Sentinel reports.

The DEA effort is aimed at cracking down on the country’s prescription drug abuse epidemic, the article notes. The agency will not confirm its involvement in the investigation, but both shipping companies have disclosed the probe in corporate filings, according to the newspaper.

Federal officials want the companies to take responsibility for the prescription drugs inside the packages they are shipping, the article states. FedEx spokesman Patrick Fitzgerald responded, “We are a transportation company — we are not law enforcement, we are not doctors and we are not pharmacists.” He added, “We have no interest in violating the privacy of our customers by opening and inspecting their packages in an attempt to determine the legality of the contents. We stand ready and willing to support and assist law enforcement. We cannot, however, do their jobs for them.”

Fitzgerald said FedEx asked the DEA to provide a list of online pharmacies that are suspected of illegal activity, so it can stop doing business with them. He said the agency has refused to provide a list.

UPS would not comment on the investigation, but stated in a corporate filing that it is cooperating with the probe.

Earlier this month, U.S. Representative John Mica of Florida sent a letter to DEA Administrator Michele Leonhart and Attorney General Eric Holder, asking them to recognize “the difficulty and unfairness of requiring those carriers to assume responsibility for the legality and validity of the contents of the millions of sealed packages that they pick up and deliver every day.”

Mica told the newspaper, “You can’t stop commerce; you can’t open every package. I’m only asking them [the DEA and Department of Justice] for a reasonable approach.”