Three factory owners facing murder charges in connection with Pakistan's worst-ever industrial fire have been granted protective bail.

Tuesday's fire at a garment factory in the southern port city of Karachi killed at least 264 people, with many workers trapped in the building.

Police say the building was illegally constructed and there was only one exit, with no safety measures or equipment in place to extinguish the fire before it engulfed the entire facility.

On Friday, the factory owners' defense lawyer said that a court had granted the three “protective bail,” instructing police that the owners can not be arrested for eight days. Attorney Amir Mansoob Qureshi said the judge also ordered them to surrender their passports.

Police registered a murder case against the owners on Wednesday, alleging that negligence on their part played a role in the deaths of nearly 300 workers.

Also Friday, the commerce and industry minister for Sindh province, of which Karachi is the capital, resigned. Rauf Siddiqui told the provincial governor that he wants a fair and transparent probe into the deadly fire and such an investigation can only be carried out without him at the helm of the ministry.

Separately on Friday, police arrested the son of former Pakistani Prime Minister Yousuf Raza Gilani in connection with a drug case.

Ali Musa Gilani is accused of using his political influence to pressure health ministry officials into allowing two pharmaceutical companies to exceed export quotas for ephedrine, which is used to make the illicit drug methamphetamine.

Police arrested him outside the gates of the Supreme Court Friday, just before he was to make a scheduled appearance. The high court later granted Ali Musa Gilani bail.

In June, Pakistan's Supreme Court convicted Musa's father, former Prime Minister Yousuf Raza Gilani, of contempt for failing to probe corruption allegations against the president. Gilani was later disqualified from holding office.