Authorities in Brazil are investigating reports that a 15-year-old girl was left in a police cell with 20 men for a month and repeatedly raped. The governor of the state of Para has promised there will be an exemplary punishment for those responsible for placing the girl in the cell.

Despite uncertainty about the girl's age, the governor said she should never have been left in a cell with men. Jails in Brazil are notorious for overcrowding and appalling conditions.

According to reports in the Brazilian media, the number of men in the cell with the teenage girl varied from between 20 to more than 30. Human rights groups have claimed that she was raped relentlessly and forced to have sex in order to obtain food.

The girl's father has now says that he has been threatened by police who tried to force him to provide a birth certificate showing that the girl was 20 years of age - a document which he said did not exist. The police are said to have believed at one stage that the girl was not under age.

The governor of the state of Para, Ana Julia Carepa, said the girl's age did not matter and she should not have been left in a cell with men. Media reports suggest that the girl was placed in the cell on suspicion of robbery, but human rights groups say there is uncertainty about what offence the girl was accused of and she was not formally charged.

Brazilian prisons have a very bad reputation and this is not the first time that there has been a controversy over a female prisoner being detained alongside men. However, on this occasion, the seriousness of the allegation has caused shock and considerable public anger.

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