Police guarded a Christian neighbourhood in Pakistan on Thursday, after hundreds of people fled a Muslim mob that rampaged through the streets over alleged blasphemy.

Homes and churches were burned and ransacked by a crowd of hundreds that tore through the streets in Jaranwala, on the outskirts of the industrial city of Faisalabad, on Wednesday.

Police said more than 120 people had been arrested over the violence and that officers were searching for two Christian brothers accused of desecrating the Koran.

"Children, women and old people were running. Some were running barefoot and some fled in rickshaws. There was chaos everywhere," said Pastor Javed Bhatti, one of the few Christians who had returned to survey the damage.

The crowds were ordered to protest by Muslim clerics who used mosque loudspeakers to spread news of the allegations.

At least four churches and a dozen houses and shops were burned and ransacked, their broken contents strewn across the streets, according to witnesses at the scene.

Muslims living in the predominantly Christian area gave shelter to their neighbours and pinned Koranic verses to the doors of Christian homes to prevent them from being targeted, residents of both faiths said

Locals said hundreds of people have fled the area to stay with relatives and have yet to return out of caution. (AFP)