Yaounde: Worried that her daughters' budding breasts would expose them to the risk of sexual harassment and even rape, their mother Philomene Moungang started 'ironing' their bosoms with a heated stone.

"I did it to my two girls when they were eight years old. I would take the grinding stone, heat it in the fire and press it hard on the breasts," Moungang said. "They cried and said it was painful. But I explained that it was for their own good."

Breast ironing the use of hard or heated objects or other substances to try to stunt breast growth in girls is a traditional practice in West Africa, experts say.

A new survey has revealed it is shockingly widespread in Cameroon, where one in four teenagers are subjected to the traumatic process by relatives, often hoping to lessen their sexual attractiveness.

"Breast ironing is an age-old practice in Cameroon, as well as in many other countries in West and Central Africa, including Chad, Togo, Benin, Guinea-Conakry, just to name a few," said Flavien Ndonko, an anthropologist and local representative of German development agency GTZ, which sponsored the survey.

"If society has been silent about it up to now it is because, like other harmful practices done to women such as female genital mutilation, it was thought to be good for the girl," said Ndonko. "Even the victims themselves thought it was good for them."

However, the practice has many side-affects, including severe pain and abscesses, infections, breast cancer, and even the complete disappearance of one or both breasts.

The survey of more than 5,000 girls and women aged between 10 and 82 from throughout Cameroon, published last month, estimated that 4 million women in the central African country have suffered the process.

"You ask me why I did it?" said Moungang. "When I was growing up as a little girl my mother did it to me just as all other women in the village did it to their girl children. So I thought it was just good for me to do to my own children."