A young Afghan woman who went to the police station to report being raped was then raped by the district police commissioner in his office, she alleges.

The 18-year-old, who gave her name as Mariam, was taken at gunpoint from her house in the Zareh district of Balkh province in northern Afghanistan in early July.

The man took her to a house on the same street where he and another man raped her, she said from Kabul.

"When I went with my father to report the rape case, the police commissioner ordered my father to wait outside, and took me into his office where he also raped me," she said.

After raping her, he warned her to "keep her mouth shut" or she would be killed, Mariam said.

Police commissioner Akram Zareh denied any wrongdoing.

"I am an honest policeman. I am 60. She is like my daughter," he said.

"This is a plot against me."

Mariam's father, Khairuddin, brought his daughter to the capital Kabul to draw attention to her story and seek justice.

"My daughter said that she would burn herself alive, because she could not go out of the house and could not make eye contact with anyone due to shame," Mr Khairuddin said by phone.

He said he met Afghanistan's Attorney-General who promised to investigate the case.

"Respecting her privacy, the Attorney-General asked Mariam to tell her story to a special female anti-violence officer in private," Baktash Azizi, the Attorney-General's chief of staff, said.

"After hearing the case, the Attorney-General appointed the Balkh provincial prosecutor and a special military prosecutor to investigate and present their findings as soon as possible."

Mr Zareh is still serving as the district police commissioner, and was already being investigated in another rape case, Mr Azizi said.

In Kabul, Mariam said she would not go home until he was removed from office.

"I will burn myself, but will not go back home where he is ruling. I will stay here until I get justice," she said.

Afghanistan is one of the most dangerous countries to be a woman or girl in, and a shortage of female police officers means women rarely report abuse, rights groups say.

Research indicates that more than eight in 10 women in Afghanistan have been sexually, physically or psychologically abused, but only a few thousand cases are reported each year.

Reuters