The World Health Organization said Friday that female genital cutting is a form of torture that must be stamped out, even if it is done by trained medical personnel.

The "medicalization" of ritual genital cutting fails to prevent girls from being permanently scarred, threatening their lives when they give birth later and endangering their babies, WHO said in a report.

Genital cutting "is the worst thing that a medical doctor could possibly do," said Joy Phumaphi, WHO assistant director-general and a former health minister from Botswana. "It is even worse than turning a blind eye, because you are legitimizing violation of a basic human right and violence against an innocent victim."

There can be no justification for doctors and nurses "to come and supervise the torture," Phumaphi said.

The practice — called genital mutilation by opponents — is done primarily in parts of sub-Saharan Africa and the Middle East. It is usually done on girls under 10. More than 100 million women and girls worldwide are believed to have undergone genital cutting, the U.N. health agency said.

Genital cutting usually involves removal of the clitoris. Those who practice it believe the cutting tames sexual desire and increases a girl's marriageability. Genital cutting is done by both Muslims and Christians.

An estimated 3 million women and girls undergo genital cutting each year, according to UNICEF.

"When the world is trying to save animals, when the world is trying to save plants, women in Africa are subjected to unnecessary torture in the name of tradition," said Berhane Ras-Work, president of the non-governmental group IAC, which campaigns against genital cutting. "It is a horrendous practice, it should not be allowed, it should be condemned, it should be stopped."

An increasing number of girls are being subjected to the practice by trained medical personnel, a UNICEF report said last year. While that may help prevent the spread of HIV/AIDS through the use of cleaner instruments, the WHO said it was opposed to any proposals that would endorse genital cutting.

"It's the same as attempting murder with a clean knife," Phumaphi said.

WHO's study, published in The Lancet medical journal, found that women who have suffered the most serious form of genital cutting have a 70 percent greater chance of hemorrhage after childbirth compared with women who did not undergo the procedure.

In countries where childbirth mortality rates are already high, "this particular process is practically a death sentence," Phumaphi said.

Children born to women whose genitals have been cut also are at greater risk, the study found. Depending on the severity of the genital cutting, neonatal death rates range from 15 percent to 55 percent higher than babies born to women with intact genitals.

WHO's study involved more than 28,000 women in six African countries where the practice is common — Burkina Faso, Ghana, Kenya, Nigeria, Senegal and Sudan.

Ras-Work said some countries in Africa were doing better than others in trying to end the practice. She cited Burkina Faso and Senegal as places where attitudes were being changed and genital cutting was declining.