Pakistan’s supreme court has ruled the arrest of the former prime minister Imran Khan was illegal and ordered for him to be released. The chief justice of Pakistan, Umar Ata Bandial, declared that the National Accountability Bureau (NAB) had acted in violation of the law by arresting Khan on the premises of the Islamabad high court without permission and that such actions would have a “chilling effect”. A written order released by the court stated that the “manner of execution” of Khan’s arrest was “invalid and unlawful” and had violated his right to justice. Khan was arrested by paramilitary troops on Tuesday as he entered the high court to face a corruption case. Bandial said Khan had already surrendered to the court when almost 100 rangers barged in and detained him, and he declared Khan’s arrest “unlawful” and in contempt of court. “What dignity remains of the court if 90 people entered its premises? How can any individual be arrested from court premises?” Bandial said. On Thursday evening, Khan was brought into the supreme court amid heavy security and produced before the three-judge panel. “There have been incidents of violence after your arrest,” Bandial said to him. “We want peace in the country.” Khan told the judge he was unaware of what was happening in the country. “I was caught as if I am a terrorist. How am I responsible for the protests?” he said. On the request of the judge, Khan appealed for calm from his followers. “We only want elections in the country,” he said. The judges directed Khan to appear before the Islamabad high court on Friday, where he will seek bail in several of the corruption cases against him. Though no longer a prisoner, Khan was ordered to stay in a police guesthouse overnight “as a guest” under the security of Islamabad police to ensure his protection, and told he could bring 10 people of his choice to join him. The government, led by prime minister Shehbaz Sharif, condemned the decision by the supreme court and made it clear that Khan was not safe from re-arrest after his release. “We will arrest him again. If he gets bail from the high court tomorrow, we will wait for the cancellation of bail and arrest him again,” said interior minister Rana Sanaullah. The release of Khan was a significant triumph for his Pakistan Tehreek-e-Insaf party (PTI), who had alleged his arrest was an “illegal abduction”, orchestrated by the government and the country’s powerful military establishment. Khan had enjoyed a close relationship with the military while he was in power, but after he was removed from office last year he became highly critical of the top military leaders and accused them of colluding with foreign powers to orchestrate his downfall and of attempting to assassinate him. The military has denied all of his accusations. Khan’s popularity has soared since he was removed from power, and he has regularly mobilised protests across the country to demand early general elections and the military’s removal from politics. News of his arrest being declared illegal was greeted with celebrations on the streets by his supporters. The crackdown on Khan’s PTI had continued on Thursday, with five leaders detained. The PTI spokesperson Fawad Chaudhry was arrested late on Wednesday night, despite having obtained protective bail from the courts. On Thursday, Shah Mahmood Qureshi, who served as foreign minister in Khan’s cabinet, was picked up by police, as well as the senior PTI leaders Ali Muhammad Khan and Ejaz Chaudhry. PTI’s former finance minister Asad Umar was also arrested on Wednesday. Islamabad police said the PTI leaders had been arrested “for inciting arson and violent protests under a well thought-out plan for threatening peace”. Seven cases have also been filed against PTI’s top leaders, including Khan, for an attack by PTI supporters on the home of a senior military officer. The army was deployed across Islamabad and in the states of Punjab and Khyber Pakhtunkhwa, where some of the worst violence has taken place. Police said they had arrested 1,300 people and 290 people had been injured in the violence. In the city of Peshawar, seven people were killed and dozens were injured after clashes broke out between protesters and police. One person died from smoke inhalation after a building was set on fire in Lahore, and another was shot near a military checkpoint in the city of Quetta. Among the buildings attacked by protesters was the Lahore residence of the prime minister where petrol bombs were thrown outside, as well as more than a dozen government offices. In Peshawar, protesters ransacked the offices of the election commission and set fire to cars and motorcycles. In a strongly worded address to the nation late on Wednesday, Sharif issued a warning to the rioters. “These terrorist and anti-state elements are being warned to desist from taking the law into their hands, otherwise they will be dealt with iron hands. Safeguarding the motherland and its ideology is more precious than their lives,” he said. In a statement addressing the unrest in Pakistan, the United Nations secretary general, António Guterres, called for “all parties to refrain from violence”.