Islamabad: Providing significant relief to the former prime minister, the Pakistan Supreme Court on Thursday declared Imran Khan's arrest "illegal" and ordered his immediate release after he was produced before a bench on its orders.

The order to produce 70-year-old Khan was issued by a three-member bench, comprising Chief Justice of Pakistan Umar Ata Bandial, Justice Muhammad Ali Mazhar and Justice Athar Minallah.

The bench, which heard the Pakistan Tehreek-e-Insaf chairman's plea against his arrest in the Al-Qadir Trust case, expressed anger at the way Khan was taken into custody from the premises of the Islamabad High Court.

The bench had directed the National Accountability Bureau (NAB) to produce Khan by 4.30 pm (local time) when the court would reconvene.

Khan was produced before the court amid tight security. As he entered the courtroom, it was closed, and subsequently, the bench resumed the hearing of the case.

"It is good to see you," Chief Justice Bandial told Khan.

"We believe that Imran Khan's arrest was illegal," the top judge said.

He said that the Islamabad High Court should hear the case on Friday. "You will have to accept whatever the high court decides," the judge added.

Bandial also said that it is every politician's responsibility to ensure law and order.

Earlier in the day, Bandial asked how an individual could be arrested from the court premises. Justice Minallah observed that Khan had indeed entered the court premises. "How can anyone be denied the right to justice? he asked.

The court also observed that no one could be arrested from the court without the permission of the court's registrar. It observed that the arrest was tantamount to denying access to justice without fear and intimation, which was the right of every citizen.

It also said that entering the premises of a court means surrendering to the court and how a person could be arrested after surrender. If an individual surrendered to the court, then what does arresting them mean? the chief justice said.

Khan's counsel Hamid Khan informed the court that his client had approached the Islamabad High Court (IHC) seeking a pre-arrest bail but was arrested by paramilitary Rangers.

"Rangers misbehaved with Imran Khan and arrested him," the lawyer said.

The court also took note of about 90 to 100 Rangers personnel entering the court to arrest Khan. What dignity remains of the court if 90 people entered its premises? How can any individual be arrested from court premises? the chief Justice asked.

Chief Justice Bandial also observed that the National Accountability Bureau had committed contempt of court. They should have taken permission from the court's registrar before the arrest. Court staffers were also subjected to abuse, he said.

Khan was arrested on Tuesday from the Islamabad High Court and an accountability court on Wednesday handed him over to the National Accountability Bureau for eight days in connection with the Al-Qadir Trust case.

The former premier on Wednesday approached the apex court to set aside the warrants of NAB of May 1 for his arrest and to challenge the Islamabad High Court's decision to declare the arrest unlawful.

Earlier, the IHC expressing anger at the way Khan was nabbed upheld his arrest hours after he was whisked away.

(With PTI inputs)