The Health, Labor and Welfare Ministry will ban individuals from importing an abortion drug without a doctor's prescription.

The drug is Mifepristone, also known as RU-486, a synthetic steroid used to chemically terminate pregnancies less than 50 days after conception.

In a rare move to ban such imports by individuals, the ministry posted details about the drug on its Web site on Monday and called on the public not to buy the drug over the Internet or use it without careful consideration of their health.

The ministry also urged the Japan Association of Obstetricians and Gynecologists to ask its member doctors nationwide to report to local health centers any cases of health problems caused by the drug, it said.

The ministry said it will ask customs officials nationwide to confirm that individuals bringing in the drug have a doctor's prescription, even though in Japan the import by individuals of small amounts of such unauthorized drugs for personal use is permitted.

Originally developed in France, Mifepristone comes in the form of a white powder or pills and is taken orally. It has not been approved for use in Japan.

It works by competitive interaction with endogenous and exogenous progesterone, one of the hormones that affects the female reproductive system, at receptor sites.

The drug is not to be used in cases of ectopic pregnancy, adrenal failure, hemorrhagic disorders, anticoagulant or corticosteroid therapy.

Side effects include an excessive amount of abdominal pain and vaginal bleeding, with the possibility of nausea, vomiting and fever. Incomplete termination of a pregnancy would require further intervention by a doctor.