SYDNEY, DEC. 4 (FRIDAY) -- Two frozen embryos of an American couple who died in a plane crash in 1983 will be thawed and, if still alive, will be given to childless couples, the state government of Victoria ruled yesterday.

Special legislation will be passed to settle the legal and ethical dilemma of what to do about the orphaned embryos, Minister for Health David White said.

White was named legal guardian of the frozen embryos, deposited in 1981 at Melbourne's Queen Victoria Medical Center by Elsa and Mario Rios.

The millionaire couple from California, who joined the center's in-vitro fertilization program, regarded as one of the most advanced in the world, died in an air crash in Chile in 1983.

Doctors in the program for infertile couples take eggs from the woman's ovary and fertilize them in a laboratory dish with sperm from her husband or another donor. After an embryo has begun to grow, it is implanted in the woman's uterus. Other embryos are frozen to be used later if a pregnancy does not result.

Ova from Elsa Rios were fertilized with sperm from an anonymous donor. The first attempt at implantation did not result in pregnancy and the two remaining embryos were left behind frozen in liquid nitrogen.

The odds are slim that the embryos will survive, White said.

"When they are thawed, the chance of them being in a state that is viable or alive . . . ready and available to be used . . . is about 5 percent."

Since the Rioses' death, a controversy has raged over what to do with the embryos. The debate intensified when a study committee initially recommended that they be destroyed, an idea that was quickly abandoned in the face of vociferous public protests.

Experts and the public debated whether the embryos should be discarded or whether a new recipient should be found for fertilization. If conception occurs, it was asked if the child or children would be eligible to inherit the sizable Rios fortune. When the case was publicized, dozens of women volunteered to be implanted with the embryos.

After lengthy legal debate and consultations with American lawyers, the Victoria government has decided that the embryos will be thawed and adoptive parents sought. But no inheritance of the Rios estate, estimated at $8 million at the time of their death, will be involved.

"We are looking for a potential recipient from the existing {in vitro} program and the embryos will remain in storage until the recipient is found," White said at a news conference. Potential recipients of the embryos have to be infertile married couples who have been in the in-vitro fertilization program for 12 months.

Children born of a successful implantation of the embryos would not be considered relatives of the surviving members of the Rios family and would not be legal heirs to the Rios estate, he said.

In May 1985, a California superior court declined to appoint guardians for the embryos and declared Elvira Abeliera, Elsa Rios' mother, the sole heir to her estate.

White ruled out any experimentation on the frozen embryos if no suitable recipient is found.

To prevent future problems, legislation will be enacted next February requiring couples having embryos frozen to state what should happen to those embryos in case the couples die.