Image copyright Getty Images Image caption Afzal Kohistani had warned his life was in danger

Pakistani activists are calling for a high-level judicial inquiry into the murder of a whistleblower who exposed "honour killings" in the country.

Afzal Kohistani had warned for years his life was in danger after he brought public attention to the apparent killing of women seen clapping and singing in a video of men dancing.

A day after his murder, his family were shocked by the arrest of his nephew.

They say he was protecting Mr Kohistani and fired at his attackers.

Mr Kohistani was shot dead on Wednesday in the city of Abbottabad, in north-western Khyber Pakhtunkhwa province. He first emerged into the public eye in 2012 by calling for justice in a case involving his family in remote Kohistan district.

Two of his younger brothers were seen dancing in a wedding video that also showed four women singing and clapping. The four women, along with a fifth, were later killed for "breaching the honour" of their family, it is alleged.

Media playback is unsupported on your device Media caption Video showed the women and men singing and dancing at a wedding, as Orla Guerin reported in 2012

Such "honour killings" occur regularly in Pakistan, especially in rural areas, and Mr Kohistani's decision to expose the alleged murders sparked a blood feud, with three of his other brothers later killed.

Activist groups that supported Mr Kohistani's long fight for justice have called on the courts to open an inquiry into his murder, and question authorities in Khyber Pakhtunkhwa province as to why they did not provide him with protection, despite several requests.

Human rights activist Qamar Nadeem told the BBC that civil society groups across the province were co-ordinating and "soon a meeting of the wider community would be held to evolve a joint strategy on the issue".

Image copyright EPA Image caption Relatives gathered outside a police station in Abbottabad on Thursday

Meanwhile, Mr Kohistani's family are calling for the release of his detained nephew, 23-year-old Faizur Rahman, and police protection for his wife and children.

Afzal's Kohistani's younger brother, Bin Yasir, who was seen dancing in the Kohistan video, has also emerged in the wake of his brother's murder after seven years in hiding.

He staged a protest outside a police station in Abbottabad and demanded the release of Mr Rahman, who was produced in court on Friday and will be held for questioning.

On Thursday, police officials told the BBC Mr Rahman had been arrested after police found a pistol on him.

In a written statement given to police and seen by the BBC, Faizur Rahman identifies three men from the family's village in Kohistan who allegedly shot Mr Kohistani on Wednesday.

He said he and Afzal Kohistani were sitting in a stationary van when the men arrived and opened fire.

He pulled out Mr Kohistani's pistol, a licensed weapon the activist carried on him in view of the threats to his life, and chased the attackers, firing some shots, he said.

According to police, at least three bystanders were injured, one of whom has said he was hit by a bullet fired by Mr Rahman.

On Friday police arrested a suspect in Kohistan's Palas district in connection with the murder, according to local media reports.

What is an 'honour killing'?

It is the killing of a member of a family who is perceived to have brought dishonour upon relatives.

Pressure group Human Rights Watch says the most common reasons are that the victim:

refused to enter into an arranged marriage

was the victim of a sexual assault or rape

had sexual relations outside marriage, even if only alleged

But killings can be carried out for more trivial reasons, like dressing in a way deemed inappropriate or displaying behaviour seen as disobedient.