Mr Bhatti’s murder has left his family and other Christians devastated Hundreds of Pakistanis have gathered amid tight security in the city of Faisalabad for the funeral of former minorities minister Shahbaz Bhatti.
Mr Bhatti, the only Christian in the cabinet, was shot dead on Wednesday after urging reform to blasphemy laws. The Taliban said they killed him.
Top leaders are attending the funeral service in Islamabad’s main church.
Mr Bhatti’s body will then be flown to Faisalabad in Punjab for burial in his native village of Khushpur nearby.
Wednesday’s assassination in Islamabad was the second this year of a Pakistani politician who wanted to reform the controversial blasphemy laws.
In January, Punjab Governor Salman Taseer, who had also opposed the law, was shot dead by one of his bodyguards in the capital.
The blasphemy law carries a death sentence for anyone who insults Islam. Critics say it has been used to persecute minority faiths.
Observers say Mr Bhatti’s killing leaves Pakistan’s Christians without their most prominent voice and threatens to silence debate on the blasphemy law. The government is accused of giving in to religious hardliners.
Stringent security precautions are in place for the funeral.
Shahbaz Bhatti predicted his death in a video recorded four months ago
Roads have been closed and police and paramilitary forces deployed around Fatima Church in the capital for the service for Mr Bhatti, 42, who was a Roman Catholic.
Marksmen took up positions on the roofs of nearby buildings ahead of the mass.
Pakistan is observing three days of mourning for the murdered minister and there have been protests by angry and frightened Christians across the country, condemning his killing.
Christian leaders have dismissed government promises that the killers will be caught. They say their community, and other minorities, no longer feel secure in Pakistan.
The BBC’s Syed Shoaib Hasan says Mr Bhatti has become a martyr for the local Christian community because of his outspoken stance on the blasphemy law.
But our correspondent says the government seems to lack his courage to take steps to amend what many are now calling Pakistan’s black law.
In January an MP from the governing Pakisan People’s Party (PPP), Sherry Rehman, dropped a bill to reform the law, because her party leaders would not back it.
She has all but disappeared from view amid concerns for her security.
The apparent ease with which Mr Bhatti, a PPP leader, was killed has caused great concern.
He had just left his mother’s home in a suburb of the capital when several gunmen surrounded his vehicle and riddled it with bullets in broad daylight, say witnesses.
The minister’s driver was spared before the gunmen escaped.
Mr Bhatti was without guards or the security escort that is standard for all Pakistani ministers, and it is not clear why. Police and federal officials are investigating.
Even before his assassination, Mr Bhatti had predicted his own death in a chilling video. He had told the BBC he had been denied more protection but would defy the death threats from Islamist militants for his efforts to reform the blasphemy law.
The law has been in the spotlight since a Christian, Asia Bibi, was sentenced to hang in Punjab last November. She denies insulting the Prophet Muhammad.
Christians make up an estimated 1.5% of Pakistan’s 185 million population.
This article is from the BBC News website. © British Broadcasting Corporation, The BBC is not responsible for the content of external internet sites.