A Pakistani rights activist whose politician father was assassinated in 2011 for supposedly insulting Islam says he fears the same fate after a hardline religious group issued a fatwa demanding his execution and the police launched an investigation into allegations he had committed blasphemy.

Shaan Taseer said the Sunni Tehreek, a grouping of clerics drawn from the Barelvi movement, was “gunning for my blood and provoking people to take my life” over a Christmas video he posted on social media in which he criticised Pakistan’s blasphemy laws.

His father, Salmaan Taseer, the former governor of Punjab province, was killed amid similar controversy by one of his own police guards six years ago.

The governor had infuriated hardliners with his demand for a government pardon for Asia Bibi, a poor Christian woman sentenced to death for blasphemy despite weak and contradictory evidence against her.

His killer, Mumtaz Qadri, became a hero, and an estimated 100,000 mourners attended his funeral following his execution last year.

The ire of the Barelvi sect, which on non-blasphemy issues is generally considered moderate, was rekindled last month after Taseer published a video expressing solidarity with people entangled in blasphemy allegations.

He called for the release of both Bibi, who remains on death row, and Nabeel Masih, a Christian teenager arrested last year for “liking” on Facebook a picture of the Kaaba in Mecca, Islam’s holiest site.

Taseer also demanded the repeal of what he called the “inhumane” blasphemy laws, a longstanding demand of international human rights groups who say the laws are widely abused by people who level false allegations to settle personal scores.

The video prompted Sunni Tehreek to issue a fatwa, or religious edict, saying Taseer was liable for death because he had supposedly committed both blasphemy and apostasy.

Police in the city of Lahore also lodged a first investigation report (FIR), a document that formally starts the process of investigating a crime, under the country’s blasphemy laws.

According to the FIR, police claimed to have found the video on a USB drive left outside a police station.

Mujahid Abdul Rasul, a Sunnit Tehreek cleric who demanded the police take action, said Taseer’s support for Bibi and Masih meant he “was equally involved in the crime” of blasphemy.

“I don’t know why the Taseer family do this again and again,” he said. “His own father was killed for this so why is he also choosing the same path?”

Taseer has not been named in the FIR, with officers at Islampura police station in Lahore claiming they had not been able to confirm if it was really him in the video.

Whether or not the police pursue the matter, the mere accusation of blasphemy can be enough to incite vigilante attacks.

Taseer, who lives abroad but visits Pakistan regularly, said the Sunni Tehreek was deliberately trying to provoke its supporters in the hope that someone would mimic the killing of his father, which took place in an Islamabad market on 4 January 2011.

“On social media there are calls for another Mumtaz Qadri to deal with me and people are offering to be his successor,” he said. “What they plan to do is engineer another Qadri-like assassination.”

Pakistan’s supreme court is due to rule on Bibi’s final appeal, which was postponed in October after one of the judges recused himself from the case.