A Muslim scholar and his two brothers have been arrested for allegedly raping their child sister and swearing her to silence on the Koran in Pakistan.

The religious scholar is alleged to have raped his 15-year-old sister at a mosque last Friday, police in Islamabad said.

Police said the three brothers - aged between 22 and 30 - told their sister to stay quiet in the name of the Koran.

They were hauled into custody and remanded at the Adiala jail on Thursday.

The Adiala jail in Rawalpindi, south of Islamabad, where police say they have detained the three suspects (file photo)

Inspector Arshad Ali said a friend of the victim's late father - a doctor - had summoned them to his clinic, Dawn reported.

The police took a statement from the victim there and accounts from doctors and local elders who claimed the three men had confessed to the crime.

According to the authorities, the victim - the youngest of nine siblings from Bannu - lived with her brothers after their parents died.

She was said to have first been raped two years ago by one of the suspects, the Karachi daily reported.

The girl was subsequently raped three times by another suspect and then most recently at the mosque, the police claimed.

The Pakistani capital of Islamabad, where authorities say they are holding three men on suspicion of raping their 15-year-old sister

After the alleged rape at the religious seminary she absconded and visited her father's friend for treatment.

When he inquired about her disappearance she informed him of the alleged assaults.

A civil court has ordered that the victim be taken to a protection centre until further notice.