About 50 people have been arrested in this eastern Pakistani city after a mob torched over 150 homes of the minority Christian community in search of an alleged blasphemer.

Police officials said they had arrested about 50 people who had been identified from video footage of the attack or named by the victims. Raids were being conducted for other wanted persons, they said.

Trouble began at Joseph Colony on Friday, when over 2,000 enraged Muslims surrounded the neighbourhood and pelted stones at the homes of Christians. The mob was led by Shafiq Ahmed, who claimed he was looking for a Christian named Savan Masih as he had allegedly committed blasphemy by insulting the Prophet Mohammed.

Some men found Masih's 65-year-old father Chaman Masih and assaulted him and then burnt his home. The mob dispersed after a police contingent was posted in the area and officials said they had registered an FIR against Masih under the blasphemy law.