A 30-year-old man in Pakistan has been sentenced to death after conviction for committing “blasphemy” on Facebook, the latest incident in the country's widening crackdown on dissent on social media.

An anti-terrorism court in the city of Bahawalpur on Saturday sentenced Taimoor Raza, 30, after he was found guilty of making derogatory remarks about the prophet Muhammad, his wives and others, prosecutors said.

The details of Raza’s specific comments were unclear. But the sentence was the first such death sentence for a Facebook post in Pakistan.

Pakistan’s harsh anti-blasphemy law provides for due process and trial, but executions happen rarely. Human rights advocates have raised concerns that the law can be misused to attack personal enemies or kick off riots.

Raza’s brother, Waseem Abbas, told the Guardian newspaper that the family were poor but literate members of the country’s minority Shiite Muslim community.

“My brother indulged in a sectarian debate on Facebook with a person, who we later come to know was an official with the name of Muhammad Usman,” he said.

The conviction comes amid rising cultural and religious tension in Pakistan, a majority Muslim country, over blasphemy.

The Pakistan government has launched a crackdown on alleged defamation on social media in recent weeks, with Interior Minister Chaudhry Nisar Ali Khan threatening on May 23 to block all social media websites with “blasphemous content.”

Earlier in March, the government had asked Twitter and Facebook to report potentially troublesome posts to authorities.

In April, a 23-year-old journalism student named Mashal Khan was fatally beaten by a mob at his college in northwestern Pakistan after rumors spread that he had insulted Islam.

Authorities eventually determined that the mob was egged on by university officials encouraging ultraconservative students after Khan had questioned policies at his school. The mob chanting “God is great” beat the young man to death in his dorm room.

Ultimately, 57 people were arrested in the attack.

Pakistani authorities have also detained and interrogated many social media users, including some members of major opposition parties, for allegedly posting anti-government and anti-military material.

Earlier this year, five Pakistani bloggers were detained, reportedly by Pakistani security forces, but were released unharmed, yet another reminder that freedom in the social media space in Pakistan is narrowing.