Pakistan has hanged the man who murdered a governor for defending a Christian woman on death row for allegedly insulting the prophet Mohammed and who sought reform of the blasphemy law.

Mumtaz Qadri was executed in a move that risks angering Islamist supporters who had feted him as a hero and threatened violence if he was executed.

Qadri, a former police bodyguard, shot liberal Punjab provincial governor Salman Taseer 28 times in Islamabad in 2011. He said he was angry at the politician's calls to reform the blasphemy law.

Executed: Relatives gather around the body of Mumtaz Qadri after he was executed in Rawalpindi

Qadri was hanged in a move that risks angering Islamist supporters who had feted him as a hero and threatened violence if he was executed

Civil society activists light candles on the anniversary of the death of the governor of Punjab province Salmaan Taseer, in Lahore

The governor had been vocal in his support of Asia Bibi, a Christian woman who has been sentenced to death after being found guilty of insulting the Prophet.

Within hours of the news of Qadri's execution, hundreds of supporters began gathering at the man's family home in Rawalpindi.

His body was being displayed to supporters at his family's home in the city, where paramilitary Ranger forces and police in riot gear as well as ambulances and dozens of police vehicles were stationed, an AFP reporter said.

Security was stepped up at flashpoints across the country, including Lahore and near the international airport in Karachi.

Riot police were deployed in the nearby capital Islamabad as officials braced for protests from hardliners.

Blasphemy is a hugely sensitive issue in the Islamic republic of some 200 million, and Qadri was hailed as a hero by many conservatives eager to drown out calls to soften the legislation.

Critics, including European governments, say the legislation -- which carries the death penalty -- is largely misused, with hundreds languishing in jails under false charges.

'Qadri was hanged in Adiala jail early Monday morning' in Rawalpindi, senior local police official Sajjid Gondal told AFP.

Cries were heard from inside the house where hundreds of men and women had gathered, and mosques broadcast news of the execution.

Riot police were deployed in the nearby capital Islamabad as officials braced for protests from hardliners

Pakistan Rangers stand guard as protestors block a road linking to Islamabad, to protest the execution of bodyguard Mumtaz Qadri

Qadri's father Bashir Awan said he was 'proud' of the martyrdom of his son, adding that he was ready to sacrifice all five of his other sons 'for the honour of the Prophet'

'I have no regrets,' Qadri's brother Malik Abid told AFP, tears rolling down his cheeks, while women chanted nearby.

He said the family had been called to the prison Sunday evening by officials who said Qadri was unwell.

But when they arrived, Qadri greeted them with the news that authorities had deceived them and that his execution was imminent.

'We started crying, but he hugged us and chanted 'God is great',' Abid said.

'I am proud of the martyrdom of my son,' Qadri's father Bashir Awan told AFP, adding he was ready to sacrifice all five of his other sons 'for the honour of the Prophet'.

In the port mega-city of Karachi, protesters blocked main intersections and some petrol stations were closed after Qadri supporters ordered them shut. Police said security had been tightened there and also in the eastern city of Lahore.

Taseer's son Shehryar said on Twitter the hanging was a victory for Pakistan, but not his family.

In the port mega-city of Karachi, protesters blocked main intersections and some petrol stations were closed after Qadri supporters ordered them shut

Qadri's lawyers drew on Islamic texts to argue that he was justified in killing Taseer, saying that by criticising the law the politician was himself guilty of blasphemy

'The safe return of my brother is the only victory my family wants,' he wrote, referring to his sibling Shahbaz Taseer, who was kidnapped later in 2011 -- reportedly by the Taliban -- despite being given a police escort after his father's killing.

Lawyers in Islamabad's district courts said they were going on strike in protest.

Some Twitter users hailed the execution as 'justice served'.

'A death should never be cause for any celebration but it's really difficult to feel any sympathy for this man or his vile supporters. #Qadri,' wrote user Hasan Zaidi.

Qadri's lawyers drew on Islamic texts to argue that he was justified in killing Taseer, saying that by criticising the law the politician was himself guilty of blasphemy -- an argument rejected by the lead judge.

A Supreme Court decision to uphold the death sentence last December sparked rallies. Islamist groups told those protests that if Qadri were executed those responsible should also be put to death.