SAN FRANCISCO (AP) — FedEx and UPS are disclosing that they are targets of a federal criminal investigation related to their dealings with online pharmacies.

The disclosures were made in regulatory filings over the last several weeks. FedEx spokesman Patrick Fitzgerald said Thursday federal prosecutors based in San Francisco are looking into issues “related to the transportation of packages for online pharmacies.” He denied any wrongdoing and called the probe “absurd.”

A spokesman with the U.S. attorney’s office in San Francisco didn’t respond to email and phone inquiries.

Online pharmacies have been at the center of an international crackdown on prescription drug abuse.

A federal jury in San Francisco on Thursday convicted three men of operating illegal online pharmacies that used FedEx Inc. and UPS Inc. to deliver drugs without proper prescriptions.