Thousands of religious hardliners in Pakistan defied a ban on demonstrations to rally on Wednesday in support of a man executed for murdering a popular governor over his call to reform the country's blasphemy laws.

Mumtaz Qadri was executed on February 29 last year for killing Salman Taseer, the governor of Punjab.

Qadri had been assigned as one of Taseer's bodyguards after the governor enraged the religious right by calling for reform to the country's blasphemy laws in support of a Christian woman who had been sentenced to death.

After his arrest, Qadri became a hero to many in hardline factions for his action, seen as defending Islam.

Despite the increased security on Wednesday, with included police shutting down entire roads, people thronged to a shrine glorifying Qadri on the outskirts of capital, Islamabad.

As space at the site became limited, people climbed on top of fences and ramparts to get a view of the stage. The crowd chanted slogans exalting Qadri and proclaiming Pakistan an Islamic state.

Islamabad police confirmed that the crowd was somewhere between 3,000 and 4,000 people.

"The protests were peaceful and the crowd dispersed after the speakers were done," a police official told Reuters.

On Tuesday, the Punjab government had said that protests would not be allowed to take place in the city due to a spate of bombings and attacks that have killed more than 130 people nationwide.