The Food and Drug Administration is set to announce today that meat and milk from cloned animals are "indistinguishable from that of conventionally bred animals and safe for human consumption." After a 90-day public comment period, sale of such meat and milk could become possible, a source familiar with the regulation said.

The question of whether the public would buy it is less clear.

Because of unknown health risks associated with cloning, the FDA put a voluntary moratorium on the sale of meat and milk from cloned animals in 2001. The agency's "risk assessment" to be released today includes more than 300 pages on the potential effects of allowing clones into the food supply, said the source, who is not authorized to speak publicly about the announcement.

"None of the studies ... identify any remarkable nutritionally or toxicologically important differences in the composition of the meat or milk," according to a draft of a paper to be published Jan. 1 in Theriogenology, a scientific journal on animal reproduction. The paper was written by scientists at the FDA's Center for Veterinary Medicine.

Though the safety of cloned animals may not be in question, public opinion is another matter, said Michael Fernandez of the Pew Initiative on Food and Biotechnology. A poll in September by the non-profit group found that 64 percent of people were uncomfortable with animal cloning. "It's clear that people have a set of concerns that are independent of safety," he said.

Animal cloning arrived in 1996 with the birth of Dolly the sheep. Cloning is the process of taking a single cell from an adult animal, inserting it into a hollowed-out egg from that species and using an electric shock to "trick" the egg into thinking it has been fertilized. If all goes well, the host mother gives birth to an exact copy — a genetic twin — of the adult animal.

The process is not very efficient; it requires up to 100 tries to go from egg to live birth. And clones have an increased risk of premature death and birth defects, according to the Theriogenology paper.

Cloning also is too expensive to be used to produce individual animals for slaughter, the journal article said. Instead, it's expected that cloning will be used mostly to make copies of animals with outstanding characteristics such as high milk production, excellent meat marbling or quick growth. Those clones would then be used to breed animals for market.

If the FDA does approve such sales, they will not have to be labeled as coming from cloned animals or their offspring.