The United Nation's top human rights official has condemned the killing of the only Christian member of Pakistan's federal Cabinet Wednesday.

Shahbaz Bhatti was shot dead on Wednesday in Islamabad. (Faisal Mahmood/Reuters)

UN High Commissioner for Human Rights Navi Pillay called on Pakistan's government to declare a moratorium on its blasphemy laws and order an independent review of them.

Pakistan's minority affairs minister Shahbaz Bhatti was the second high-profile opponent of blasphemy laws assassinated in two months. The laws impose the death penalty for insulting Islam.

Pillay urged Pakistan's government to "not only hold the killers to account, but reflect on how it can more effectively confront the extremism which is poisoning Pakistani society."

Bhatti, a Roman Catholic, was killed Wednesday in Islamabad after a group of gunmen sprayed his car with bullets.

The minister was dead on arrival at Shifa Hospital, hospital spokesman Asmatullah Qureshi said.

Bhatti, 42, a campaigner for human rights causes, had apparently been aware of the danger he was in and left a videotaped message with the British Broadcasting Corporation and the Al-Jazeera satellite TV station, to be broadcast in the event of his death.

In the farewell statement, Bhatti said he was threatened by the Taliban and al-Qaeda, but this would not deter him from speaking for "oppressed and marginalized persecuted Christians and other minorities" in Pakistan.

"I will die to defend their rights," he said on the tape. "These threats and these warnings cannot change my opinions and principles."

Despite the threats, Bhatti, who had been assigned bodyguards, was without protection when he visited his parents in the capital of Islamabad on Wednesday afternoon, police said

The politician had just pulled out of the driveway of his parents' house when three men standing nearby opened fire, said Gulam Rahim, a witness.

Two of the men opened the door and tried to pull Bhatti out, Rahim said, while a third man fired his Kalashnikov rifle repeatedly into the dark-coloured Toyota, shattering the windows with bullets.

The gunmen then sped away in a white Suzuki Mehran car, said Rahim, who took shelter behind a tree.

Bhatti called an 'infidel Christian'

In leaflets left at the scene of the shooting, al-Qaeda and the Pakistani Taliban Movement in Punjab province claimed responsibility. They blamed the government for putting Bhatti, an "infidel Christian," in charge of an unspecified committee, apparently referring to one said to be reviewing the blasphemy laws. The government has repeatedly said such a committee does not exist.

Government officials condemned the killing, but made no reference to the blasphemy law controversy.

The governor of Punjab province, Salman Taseer, was assasinated by a bodyguard in January after he called for a pardon of a Christian woman sentenced to death under those laws.

With files from CBC News