The rallygoers, gathered to express support for the country’s judiciary, accused Alam of blasphemy when he made a concluding prayer at the end of the event.
“Some words of his prayer were deemed blasphemous by a number of protestors, leading to torture and death at the hands of the angry mob,” said Khan.
Witnesses said the police deputy on duty at the rally attempted to save the man by locking him up in a nearby shop, but the mob broke through the door and attacked him.
Videos circulating on social media showed people pushing the accused man to the ground, kicking him and beating him with batons. The man died at the scene.
Police took the body into custody and said an investigation was underway.
Accusing people of blasphemy in Pakistan is common.
Last month, the Pakistani police arrested and later released a Chinese national named Tian, who was working in Pakistan on a dam project and was accused by the locals of blasphemy.
In February, an angry mob entered a police station in Pakistan’s eastern city of Lahore, snatched a person accused of blasphemy from his cell and killed him.
In 2021, a Sri Lankan national, Priyantha Diyawadanage, who was working as a factory manager in Pakistan, was killed by an angry mob over allegations of blasphemy.
In 2017, Pakistani student Mashal Khan was killed by a mob on the premises of his university over allegations of posting blasphemous content online.