Some Washington-area federal workers who are jittery about the future of their retirement program say they are getting calls at home from people offering to sell them an insurance policy that will protect their pension rights even if Congress dismantles the civil service retirement program.

The callers say they represent an outfit called the Federal Employe Supplemental Retirement Agency (FESRA), or a similar official-sounding agency. In several cases they have implied that they are an arm of the federal Office of Personnel Management.

What they would like to do, the "insurance" reps say, is to meet with the U.S. employe to discuss a plan that will give that employe the option to retire early on full benefits even if Congress raises the retirement age for civil servants, raises contributions and cuts benefits.

In the past two weeks more than a dozen federal workers have called this office to say they have been called at home by people offering pension-protection policies. Two of those reached, one an employe of Defense, another with Commerce, say that when they asked for a telephone number and address for the insurance company the "salesman" hung up.

People who have received the calls have two questions: How did the callers know their home number and agency, and is the insurance plan on the level?

Here are the results of some inquiries:

* Despite claims that the insurance plan is affiliated with the OPM, OPM officials say they have never heard of the outfit. They urge anyone getting such a call to be "very, very, very careful" before signing anything or handing over any money.

* The C&P Telephone Company says it has no listing for the FESRA.

* The Better Business Bureau says it has never heard of the FESRA.

* The congressional Federal Government Service Task Force says the "insurance" offer sounds fishy.

* The D.C. Insurance Commission says it has no record of such a group.

* The Employe Benefit Research Institute says it would take a "very creative" insurance firm to write such a policy--if benefits could be defined and agreed upon--and that premiums for such a policy would be very steep.

"You can write insurance on anything," an EBRI expert said. He said firms like the highly reputable and world-famous Lloyd's of London can and do insure virtually anything. But this isn't Lloyd's of London calling.

So if you work for Uncle Sam and get one of the calls at home, be careful.