A top judge in Pakistan, hearing high treason case against former military president, Pervez Musharraf, on Thursday stepped down because of defence lawyers' accusations of bias.

Musharraf's defence lawyers had alleged that head of the three- member special court, Justice Faisal Arab, is not impartial.

The decision has temporarily halted the proceedings and the Chief Justice of Supreme Court could nominate another judge to lead the bench. Another judge from the bench could also be nominated to lead it, legal experts say.

Musharraf's lawyers were of the view that Justice Arab had once refused to take oath under a constitutional order Musharraf had introduced after he suspended the constitution in 2007.

Musharraf faced high treason charges for suspending the constitution when he declared emergency rule in 2007.

Defence lawyer Anwar Mansoor said Thursday that he is not satisfied with the way the case is being heard. He reiterated his criticism towards the issuance of non-baiable arrest warrant for his client.

The court in an early verdict this month had rejected all objections at the court's formation, the bias of its judges and procedure of the judge's nomination.

Musharraf's lawyers have raised objections to the appointment of special prosecutor, Akram Shaikh, who had insisted on issuance of non-bailable arrest warrant after Musharraf did not appear before the court despite several orders.

Musharraf's another defence lawyer Ahmed Raza Kasuri told reporters that the defence team had told the bench they are not comfortable with the proceedings.

On this, Justice Arab walked out of the proceedings and said he is announcing to step aside from the case.

Earlier, the former president had challenged jurisdiction of the special court and his defense lawyers had argued that only a military court can try Musharraf under army act.

Musharraf's lawyers had insisted that their client had imposed emergency when he was the army chief and that a military court can only try him under military act.

A previous ruling stated that Musharraf is now a retired man and he is no more a subject of military laws.

Musharraf had taken over in a bloodless coup when he had dismissed the government of Prime Minister Nawaz Sharif in 1999.

Musharraf, who had resigned in 2008 as president and had gone into exile, returned to Pakistan in March this year to run in parliamentary elections. However, a court disqualified him from competing in the May elections.

The court issued bailable arrest warrant for Musharraf on Jan. 31 after he failed to appear at previous hearings despite several orders. Legal experts are now of the view that the arrest warrant and other verdicts stand null and void.