A man was beaten to death by a mob after being accused of blasphemy at a rally for former Pakistan prime minister Imran Khan's party, Pakistan Tehreek-e-Insaf (PTI), officials said Sunday.

Blasphemy is a hugely sensitive issue in Muslim-majority Pakistan, where even unproven allegations can stir mobs and violence.

Video of the lynching has been shared widely on social media, with police seen vainly trying to stop a frenzied mob from beating the alleged blasphemer.

The incident took place on Saturday in the Sawal Dher area of Mardan city in the country's ultra-conservative northwestern Khyber Pakhtunkhwa province bordering Afghanistan.

Police said a man identified as Nigar Alam was asked to deliver the concluding prayer at a rally organised by PTI when the crowd took offence to his comments.

He managed to flee the scene, police said, but a mob tracked him down to a relative's house.

"A group of individuals climbed over the wall, barged inside, and beat him to death with sticks and batons," said district police chief Najeeb-ur-Rehman

"The mob was so agitated that it became extremely challenging for the police to even recover the body," he told AFP.

Few issues in Pakistan are as galvanising as blasphemy, and even the slightest suggestion of an insult to Islam can supercharge protests and incite lynchings.

According to the Centre for Social Justice -- an independent group advocating for the rights of minorities -– more than 2,000 people have been accused of committing blasphemy since 1987, and at least 88 people killed by lynch mobs for similar allegations.

Rights groups say accusations of blasphemy are often wielded in Pakistan to settle personal vendettas, with minorities largely the targets.