KABUL — An Afghan child bride who says she was tortured by her mother-in-law and locked in a toilet for six months will be sent to India for medical treatment, the government in Kabul said on Monday.

Sahar Gul, 15, was beaten, had her fingernails pulled out and was burned with cigarettes after she defied her in-laws who tried to force her into prostitution. She was left barely able to speak after her ordeal.

The girl, who was found in the basement of her husband's house in the northeastern Baghlan province late last month, had been sold by her brother to her husband about seven months ago for $5,000.

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

Interior ministry spokesman Sediq Sediqui said: "The government is sending her to India for further treatment. She will be treated for her wounds.

"Her mother-in-law and sister-in-law have been arrested, the police are after her husband and father-in-law who are at large, they will be arrested soon."

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

President Hamid Karzai's office said in a statement that the interior ministry had launched an investigation into the "tortures and violence against Sahar Gul".

"The president, in raising this issue to the national security council meeting, assigned the deputy interior minister to arrest the culprits as soon as possible and bring them to justice", the statement said.

The teenager had previously told Afghan health minister Dr Suraya Dalil from a hospital bed in Kabul: "For several months I was locked up in toilet by my in-laws and particularly my mother-in-law.

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

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.

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