Announcing a new mail campaign to thwart telemarketing fraud, President Clinton said yesterday that many older Americans face a greater threat from "a scam artist on the phone" than from a mugger on the street.

In his weekly radio address, Clinton announced that every American household will soon receive a postcard with tips on avoiding telemarketing rip-offs.

"This is the largest consumer protection mailing in our history," Clinton said. "It will provide information you can keep by the phone to help you distinguish between fraudulent and legitimate telemarketers."

The postcards, to begin arriving Nov. 15, will include a set of warnings, such as telling people to avoid giving unknown callers important financial information.

Clinton also directed Attorney General Janet Reno to send him a plan to combat consumer fraud and to increase prevention and enforcement.

"To many of our most vulnerable citizens, especially our seniors, the greatest threat may not come from a criminal on the street but from a scam artist on the phone," the president said.

The FBI has reported that telemarketing fraud takes between $40 billion and $60 billion a year from Americans.

Clinton said a toll-free telephone number soon will be available for victims of telemarketing fraud, but people can now receive prevention tips and file complaints on the Internet at www.consumer.gov.