n a possible political setback for stem cell research, the National Institutes of Health has been told to postpone the first meeting of a committee to review grant applications for research on human embryonic stem cells.

The N.I.H. was told by its parent agency, the Department of Health and Human Services, to put off the meeting until the department has completed a review of the legal basis for research with the cells, which hold promise of new therapies because they can generate all the tissues of the body.

Bill Hall, the department's spokesman, said the meeting was simply postponed until the legal review was completed some time this summer, and that research would not necessarily be delayed, given the length of the N.I.H.'s review process. The postponement, which was not announced, was reported by The Washington Post on Saturday.

Advocates of the research are uncertain whether the move is the simple administrative step the department suggests, or a first step toward banning the research altogether.

If the administration had done nothing, the N.I.H. would have proceeded to review grant applications and finance those that were successful, under the course set by the Clinton administration. This process has now been halted.

But the postponement does not necessarily mean that the administration will curtail embryonic stem cell research. Former President Bill Clinton lifted the ban on fetal tissue research during his first few days in office and President Bush could have acted as summarily against embryonic stem cell research if he had wished to do so. That he has not "is a good sign and shows the administration understands that this is a complex issue," said Lawrence Soler, a chairman of the Coalition for the Advancement of Medical Research.

Congress has forbidden the use of federal funds for any research in which a human embryo is destroyed. Under the Clinton administration, the department's general counsel, Harriet Rabb, ruled that federal funds could be used to do research on the cells, but not to derive them. It is this ruling that is under review.

The cells are derived from embryos created in fertility clinics but not needed by the parents. Because the cells derived from the embryos can grow and multiply indefinitely, a limited number of embryos would fulfill researchers' needs. Biologists hope that the cells will serve as a universal repair material for treating diabetes, Parkinson's and many other serious diseases.

But opponents of abortion oppose the research because embryos must be destroyed to generate the cells.