A welfare policy group has charged that some federal agencies are providing slots for welfare clients to work off their benefits under "workfare" programs, despite a ruling that it is illegal for federal agencies to put them in nonpaying jobs.

Jobs Watch, a unit of the Catholic University Law School Center for National Policy Review, said that Army and Navy recruiting stations in Milwaukee, as well as the Veterans Administration hospital there, have been using welfare clients in various jobs. Under workfare, people on welfare work for public agencies without additional compensation.

Two years ago, the Reagan administration achieved the passage of legislation allowing states to institute workfare programs for people receiving federal-state support under the Aid to Families with Dependent Children program.

However, the general counsel's office of the Health and Human Services Department, which administers the AFDC program, recently ruled that federal agencies may not legally "host" workfare programs.

Undersecretary John A. Svahn has asked the General Accounting Office to review the ruling, and Congress has been asked to overturn it. But if it stands, it will mean that only local and state government agencies may "host" welfare clients in workfare slots.

An Army spokesman said a preliminary inquiry indicated that welfare clients may have been used in the past in a Milwaukee recruiting station but apparently are not now.

However, the VA said that it has been using welfare clients for two years at the Wood VA Medical Center in Milwaukee and that about 70 people are now in such jobs.

The staff assistant director at Wood said its workfare employes are on the county general assistance program rather than AFDC and that the VA general counsel indicated in 1978 that using such people "is kosher."