CHICAGO, JUNE 28 -- The controversial French abortion pill, RU-486, has won backing from the American Medical Association, the nation's largest doctors association.

In a voice vote Wednesday, the AMA's 436-member policy-making House of Delegates endorsed testing and possible use of RU-486. Some doctors said the pill appears safer and cheaper than surgical abortion and may be useful in treating brain tumors, breast cancer and other illnesses.

"The abortion issue, pro and con, should not interfere with our ability to conduct all kinds of investigations for all kinds of problems," said Charles Sherman, chairman of the AMA committee that recommended support for the pill.

The pill is not available in the United States, and no U.S. company has applied for Food and Drug Administration approval to market it in this country.

A leading abortion opponent attacked the AMA action. "I think it is outrageous for doctors to be thinking up better ways for killing their little patients," John C. Willke, president of National Right to Life, said in a telephone interview.

The director of the Washington-based Reproductive Health Technologies Project, a coalition of abortion-rights, family planning and women's health groups, welcomed the AMA move. "It's extremely important that the AMA, representing the mainstream medical community in the country, has spoken out," Marie Bass said.

RU-486 causes the uterus to shed its lining, as occurs in menstruation, and expel a fertilized egg.