An Afghan child bride has spoken of how she was tortured by her in-laws for months.

15-year-old Sahar Gul, who is recovering in a Kabul hospital, said she had been locked in a toilet, beaten, burned with cigarettes and had fingernails pulled out.

Police said she was locked up when she defied her in-laws who tried to force her into prostitution.

Her brother had sold her to her husband about seven months ago for $5,000.

"For several months I was locked up in toilet by my in-laws and particularly my mother-in-law," she told media during a visit from Afghan health minister Dr Suraya Dalil.

"I was denied food and water. I was tortured and beaten."

The minister said it was an example of "increased cases of violence against women in Afghanistan".

Women continue to suffer in Afghanistan despite billions of dollars of international aid that has poured into the country during the decade-long war.

The minister said Ms Gul was suffering from severe blood loss, with multiple burns and injuries. "She is also suffering from trauma and psychological problems," she said.

"She is still a child, below the legal age of marriage. She is only 15 and from a remote part of the country. It's a tragic and heartbreaking story for Afghanistan."

The teenager was found in the basement of her husband's house in the northeastern Baghlan province late on Monday.

Her family, from the neighbouring province of Badakhshan, reported her disappearance to police after being denied access to the home.

Three women, including the girl's mother-in-law, were arrested over the case, but her husband fled.

The Afghan Independent Human Rights Commission logged 1,026 cases of violence against women in the second quarter of 2011, compared with 2,700 cases for the whole of 2010.

According to figures in an Oxfam report in October, 87% of Afghan women report having experienced physical, sexual or psychological violence or forced marriage.

In November, the United Nations said that a landmark law aiming to protect women against violence in Afghanistan had been used to prosecute just over 100 cases since being enacted two years ago.