Gunmen shot dead Pakistan's minority affairs minister in Islamabad, police and a hospital doctor said, after the Christian politician had complained of death threats.
Shahbaz Bhatti, a Catholic, had been a vocal opponent of Pakistan's controversial blasphemy law.
His death comes two months after the governor of Punjab province, who also campaigned against the law, was assassinated.
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Unknown assailants sprayed bullets on Bhatti's car in a residential district of the Pakistani capital before fleeing, police official Abdul Majid told AFP.
He was dead on arrival at Islamabad's Shifa hospital, doctor Azmatullah Qureshi said.
The murder comes after the January assassination of liberal Punjab governor Salman Taseer by one of his police bodyguards. Bhatti had said he too had been threatened over his opposition to the blasphemy law.
Pakistan's law against blaspheming Islam carries the death penalty.
While no one has ever been sent to the gallows for the crime, activists say the law is used to exploit others out of personal enmity or business disputes.
