Pakistani authorities barred the family of murdered social media celebrity Qandeel Baloch from legally "forgiving" their son, who is accused of strangling his sister, sources said.

A police source told the Reuters news agency on Monday that the government in Punjab, in a rare decision, has barred the family from forgiving their son after he confessed to murdering 26-year-old Baloch on Friday.

"It was done on the instructions of the government. But it happens rarely," a Punjab police official told Reuters.

The practice of "forgiving" is a common legal loophole that sees many honour killings go unpunished in Pakistan.

READ MORE: Pakistanis on Qandeel Baloch - the problem is society

Baloch was found dead in her family home, having been strangled by her brother, Waseem Azeem, who later said he had "no regrets" and confessed to killing his famous sister for violating the family's honour with her provocative social media posts.

It was not immediately clear if the Punjab government's decision would lead to any meaningful reforms.

The slain woman's father, Muhammad Azeem, filed a police complaint against Waseem and another one of his sons for their role in the murder.

Police on Monday also said they were widening their investigations to include a leading Muslim scholar, Mufti Abdul Qavi, who was removed from a prominent Muslim committee after a video showed Baloch sitting on the scholar's lap, while photos show her wearing his traditional wool cap.

READ MORE: Pakistan - Laws fail to check violence against women

More than 500 people, mostly women, die in Pakistan each year in such killings. They are usually carried out by members of the victim's family meting out punishment for bringing so-called "shame" on the community.

Prime Minister Nawaz Sharif in February promised to speed up the passage of a law to tackle honour killings but right groups say there has been no progress.

Baloch built a modelling career on the back of her social media fame and was the family breadwinner.

Media often described her as Pakistan's Kim Kardashian and she called herself a modern-day feminist. However, she faced frequent abuse and death threats for her pictures and videos, but continued to post material on social media.

READ MORE: Anger after honour killing of Qandeel Baloch

Many condemned the killing outright, others said she deserved to be killed, and some said while she should not have been killed, they could understand the brother's motive.

Before her death, Baloch spoke of worries about her safety and had appealed to the interior ministry to provide her with security for protection. No help was provided and the interior ministry has not commented on her murder.