SAN FRANCISCO — Federal authorities on Thursday charged FedEx with assisting illegal pharmacies by knowingly delivering painkillers and other dangerous drugs to customers without prescriptions.

The indictment was filed in federal court in San Francisco, and the Department of Justice announced the charges in Washington, D.C. The indictment alleges that FedEx conspired with two related online pharmacies for 10 years ending in 2010.

The Memphis, Tenn.-based delivery company is accused of shipping powerful sleeping aid Ambien, anti-anxiety medications Valium and Xanax, and other drugs to customers who had no legitimate medical need and lacked valid prescriptions.