A Pakistani court on Monday prevented the government from granting a swift pardon to a Christian mother sentenced to death for insulting the Prophet Mohammed, a lawyer said.

Lawyers petitioned the top court in Punjab province not to allow President Asif Ali Zardari to pardon Aasia Bibi while her case was pending in the courts.

Pope Benedict XVI has called for her release and political pressure has been growing for a pardon, but conservative Muslims have threatened anarchy if the government grants clemency to Bibi, mobilising protestors onto the streets.

She was sentenced on November 8 to hang under controversial blasphemy laws that rights activists say encourage Islamist extremism.

Bibi can be executed only if the Lahore high court upholds her sentence on appeal. No date has yet been set for the appeal hearing.

"We argued that since the death sentence given by the trial court to Aasia Bibi has yet to be confirmed or rejected by the high court, the president could not use his power at this stage," lawyer Allah Bakhsh Leghari told AFP.

"The court has to evaluate the facts and until it does so, president cannot give any decision," he added.

The Lahore high court chief justice, Khawaja Sharif, ordered the provincial governor and federal government to respond to the petition and adjourned the hearing until December 6, Leghari said.

"Since the matter is in the high court, the government cannot now make any move to pardon Bibi," he added.

Most of those convicted of blasphemy in Pakistan have their sentences overturned or commuted on appeal through the courts.

Bibi was arrested in June 2009 after Muslim women claimed that she made derogatory remarks about the Prophet Mohammed. Bibi was set upon by a mob, arrested by police and sentenced on November 8.

Rights activists and pressure groups say it is the first time that a woman has been sentenced to hang in Pakistan for blasphemy.