A 15-year-old Afghan girl who was severely tortured for months by her in-laws to force her into prostitution will be sent to India for medical treatment, an Afghan official has said.

Sahar Gul's mother-in-law and sister-in-law have been arrested and her husband is being sought, said interior ministry spokesman Sediq Sediqi on Monday.

The case has shocked Afghans, though rights activists say serious abuses against women and girls in the conservative society are common. President Hamid Karzai has said that whoever used violence against Gul will be punished.

According to officials in north-eastern Baghlan province, Gul's in-laws kept her in a basement for six months, ripped her fingernails out, tortured her with hot irons and broke her fingers. Police freed her last week after her uncle tipped them off.

The public health and women's affairs ministers visited Gul, who is in a Kabul hospital.

"It is a violent act that is unacceptable in the 21st century," Sediqi told reporters. "We are thankful [to] Sahar Gul's uncle." He added that "if the police had not arrived in time she may have died".

Gul was married about seven months ago. Jawad Basharat, spokesman for the provincial police chief in Baghlan, said an arrest warrant had been issued for her husband, who is serving in the Afghan army.

"After police found out about the small girl Sahar Gul they took action and found her in the basement of the house in very bad condition," Basharat said. "Her nails were pulled out, she has injuries in all parts of her body, there are signs of burning on her body, she was suffering from different kinds of injuries."

He said that her mother-in-law and other members of the family were reportedly involved in "criminal activities", which he said included prostitution and selling alcohol.

According to preliminary reports, Basharat said they tried to force her into prostitution and she did not agree. "This was one of the reasons that they detained her in the basement for six months," he said.

Rahima Zarifi, the provincial director of women's affairs in Baghlan, said a commission had been set up under Karzai's orders to investigate the case.

Health minister Suraya Dalil said that despite progress in women's rights, work remained to be done.

"This is the very most extreme case that we have seen. That a child, that a girl child has been abused, has been physically abused, psychologically abused. It is an issue that shows that we still need to work a lot with regard to education, with regard to awareness, with regard to social and economic development," Dalil said.

Despite much progress since the fall of the Taliban 10 years ago, women's rights in Afghanistan remain a problem in a country with a strict patriarchal culture.

Under Taliban rule, girls' schools were banned and women could only leave the house accompanied by a male family member.

A UN report issued in November found that a 2009 law meant to protect Afghan women from a host of abusive practices, including rape, forced marriage and the trading of women to settle disputes, was being undermined by sporadic enforcement.

The Law on the Elimination of Violence Against Women was passed in August 2009 and had raised hopes among women's rights activists that Afghan women would get to fight back against abuses that had been ignored under Taliban rule. The law criminalised many abuses for the first time, including domestic violence, child marriage, driving a woman to resort to suicide, as well as the buying and selling of women.

Yet the report found only a small percentage of reported crimes against women were pursued by the Afghan government.

Between March 2010 and March 2011, prosecutors opened 594 investigations into crimes under the law – only 26% of the 2,299 incidents registered by the Afghan human rights commission, the UN report said. Prosecutors filed indictments in only 155 cases, or 7% of the total number of crimes reported.