Islamabad: A lawyer has filed a petition in a Pakistani court challenging the death sentence given to the killer of Punjab Governor Salmaan Taseer, even as the assassin's counsel said that his client was unwilling to file an appeal against the verdict.

Lawyer G M Chaudhry filed a petition under a Constitutional provision in the Islamabad High Court on Monday, challenging the trial and sentencing of Taseer's murderer Malik Mumtaz Hussain Qadri by an anti-terrorism court.

Qadri, a police guard who was part of Taseer's security detail, had gunned down the outspoken Punjab Governor outside a restaurant in Islamabad in January for calling for changes in the country's controversial blasphemy law.

Chaudhry contended that the Rawalpindi-based anti-terrorism court could not, under the Constitution, hear a case related to a murder committed in Islamabad.

The petition named the ministries of interior and law and justice, the judge of the Rawalpindi-based anti-terrorism court and the Punjab Home Department as respondents.

Qadri was convicted and sentenced to death on Saturday, sparking protests across the country by hardline Islamic groups.

The Islamabad High Court's office noted that Chaudhry was not an aggrieved person but said his petition might be fixed for hearing on Wednesday.

Chaudhry alleged that anti-terrorism court Judge Pervez Ali Shah had awarded the death sentence without lawful authority.

He claimed that the offence was of an ordinary nature but the trial was conducted under the Anti-Terrorism Act.

In a separate development, Qadri's lawyer Shuja-ur-Rehman said his client was unwilling to file an appeal against the death sentence given by the anti-terror court.

Rehman said he had met Qadri, who refused to approach the Lahore High Court to challenge his conviction.

Rehman said if Qadri failed to file an appeal in the High Court within two days, the lawyers would do it for him.

District Bar Association General Secretary Sardar Mansaf Bashir said the law allowed a person sentenced to death to challenge the verdict within seven days, otherwise the execution would be carried out.

He said under the law, family members of the convict or other persons could not file such an appeal.