Militants linked to the Taliban shot dead Pakistan's minorities affairs minister Shahbaz Bhatti, who was a staunch critic of the controversial blasphemy law, on Wednesday.

Four gunmen ambushed the car in which Bhatti, the lone Christian member in the Pakistani cabinet, was traveling in the capital Islamabad, according to reports.

Pakistani Taliban assumed responsibility for the murder, saying the killed minister was a blasphemer. The killing is the second high-profile assassination of critics of the blasphemy law which stipulates death penalty for anyone who insults Islam and the Prophet.

On January 4, the governor of a key Pakistani province was assassinated in broad daylight by his own body guard. Governor Salman Taseer had vehemently opposed the controversial hard-line blasphemy law under which death penalty is handed out for insulting Islam or its prophet. Human rights activists have said the law is abused by religious extremists and is also often misused by people looking to settle personal scores.

Bloomberg said Bhatti, 42-year-old a Catholic, was a former leader of Pakistan’s main minority-rights group and that he had publicly called for changes to the blasphemy law.

Pakistan's blasphemy law came into the spotlight when a court sentenced a Christian woman to death for allegedly committing blasphemy. Human rights groups had condemned the move and the assassinated governor of Punjab had spoken in favor of condoning her sentence.

Islamabad police said the minister was traveling without his security detail. There was just a private driver with him. We don't know about the minister's thinking, but we had provided him two escorts because he was under threat, police said.