A three-member bench, headed by Justice Faisal Arab, is hearing the case relating to treason charges against the former president for imposition of emergency rule in 2007.
With authorities promising fool-proof security, Arab today said the order to produce the former President in court on March 14 remained intact.
Musharraf on Tuesday failed to turn up for his indictment in the court citing security reasons and was summoned on Friday.
Musharraf's counsel Anwar Mansoor, during today's proceedings, said he cannot give arguments. He said the doctors had suggested him to take a few days of rest as he was diagnosed with food poisoning.
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Arab said the court could not coerce anyone to give arguments in a case. The judge said presenting an argument was the defence counsel's prerogative.
However, he said the court could not stop the proceedings of the case even if Mansoor did not present his arguments for a month or two.
The ISI representatives told the judges that the latest alert was issued after a call had been traced in relation to a possible attack being planned against Musharraf.
The men who briefed the judges after the hearing was adjourned said the threat to Musharraf's life was real.
Militant groups had been planning to attack Musharraf, they said.
The court had yesterday sought a briefing from the agency which had issued the threat alert hours before Musharraf's scheduled indictment in the high treason case.
Only cleared personnel will be deployed as part of Musharraf's personal security detail.
All individuals will have to go through a security check before entering the courtroom. Mobile phones, tablets and laptops will not be permitted inside the court premises.