Originally Published: 11 MAY 23 09:14 ET

Updated: 11 MAY 23 09:42 ET

By Sophia Saifi, CNN

(CNN) -- Pakistan's Supreme Court ruled on Thursday that the arrest of former Prime Minister Imran Khan was unlawful, overturning a lower court's ruling on Tuesday that it was legal.

The court ordered that Khan be released, according to officials in Khan's political party, Pakistan Tehreek-e-Insaf (PTI).

Khan was arrested on May 9 by paramilitary troops in a sudden operation that saw officers smash their way into a courthouse in the capital Islamabad to detain him on multiple corruption charges.

He was then detained in a guesthouse inside police headquarters where he appeared for a special hearing in front of a judge behind closed doors on Wednesday before being remanded in custody for eight days for a charge brought by Pakistan's anti-corruption agency.

Khan's lawyers had petitioned against judicial proceedings against their client taking place in police headquarters instead of a courthouse.

Police had justified the move, saying it was to keep Khan away from the public to maintain law and order.

Following his arrest, eight people have died and hundreds have been arrested as protests pitting his supporters against army supporters turned violent.

The former PM is accused of illegally acquiring land to construct a university and has also been charged in a separate case for unlawfully selling gifts sent to him by foreign leaders while in office.

In a pre-recorded statement released on YouTube by Khan's Pakistan Tehreek-e-Insaf (PTI) political party after his arrest, the former prime minister said he was "detained on incorrect charges" and told his supporters "the time has come for all of you to come and struggle for your rights."

Tense showdown

The former cricketer-turned-politician's arrest turbocharged what was already a tense showdown between the military and Khan's supporters that had been simmering for months.

The largest protests took place in the cities of Lahore and Peshawar, both political strongholds for Khan, and saw crowds clash with security forces.

Hundreds of protesters stormed the headquarters of the national broadcaster Radio Pakistan in Peshawar, setting the building on fire.

At least eight people have died in the clashes and more than 300 been injured, according to officials. More than 650 people have been detained in the province of Khyber Pakhunkhwa, a government official who requested not to be named, told CNN on Thursday.

Police said nearly 1,000 Khan supporters had been arrested in the country's most populous Punjab province, according to Reuters.

Private schools were ordered shut nationwide, with certain countries, including the United States, issuing travel advisories. The government blocked mobile internet services in a bid to quell the chaos, disrupting access to Twitter, Facebook and YouTube. Popular apps and digital payment systems have also been disrupted.