Federal prosecutors in the Metro East will announce a major law-enforcement action on Monday against a telemarketer that sold extended auto-service contracts, the U.S. Attorney's office for southern Illinois announced today.

Authoritites won't identify the company involved or detail allegations against it, other than to say they involve illegal robo-calling. Federal prosecutors have never filed criminal charges relating to the sale of extended service contracts.

The Post-Dispatch has reported on the existence of a federal investigation into Wentzville-based US Fidelis, which was at one point believed to be the nation's leading robo-caller. Agents from the FBI and Postal Inspection Service interviewed a former top executive, and the independent management team that has run the company since it filed for bankruptcy on March 1 have turned over company records to federal prosecutors.

However, US Fidelis was hardly the only seller of extended service contracts. At least 40 such firms have operated in recent years in the St. Louis area, a hub for the industry. And the unidentified telemarketer might have no connection to the area.

The U.S. Attorney's office for Illinois' southern district has a reputation for prosecuting consumer fraud cases involving defendants based elsewhere, including abroad. The Chicago office of the Federal Trade Commission, whose chief is scheduled to be in town Monday, has filed civil suits against California and Florida firms that tried to sell service contracts via robo-calling.

To bring charges against a company, federal prosecutors in the Metro East need only local victims.

The U.S. Attorney's office won't release any additional information until a court hearing Monday afternoon before U.S. Magistrate Judge Donald G. Wilkerson at the federal courthouse in East St. Louis