(UPI) – U.S. authorities say they've succeeded in shutting down the world's largest alleged generator of unsolicited "spam" e-mails.

Prosecutors say HerbalKing, an alleged global spam gang based in San Francisco, is responsible for billions of spam messages promoting everything from prescription drugs to "male-enhancement" pills and diet pills. A federal judge in Chicago Tuesday ordered HerbalKing's operations shut down pending a criminal trial, USA Today reported.

Acting on a complaint from the U.S. Federal Trade Commission, prosecutors allege the spam operation was overseen by Australian Lance Atkinson, 26, and Jody Smith of Texas through four companies they controlled: Inet Ventures, Tango Pay, Click Fusion and TwoBucks Trading.

The FTC complaint alleges Atkinson hired spammers on a global basis and provided them with text and hyperlinks to Web sites for his companies, with the spammers paid by commission.

USA Today said the FTC won a $2.2 million judgment against Atkinson and a partner in 2005 for running a similar spam program that marketed herbal products.