Pakistani police have arrested over 4,000 supporters of former Prime Minister Imran Khan as authorities locked down the capital ahead of a rally demanding his release from prison, officials reported on Sunday.

Imran Khan, who has been incarcerated for over a year and faces more than 150 criminal charges, remains a popular figure. His party, Pakistan Tehreek-e-Insaf (PTI), has dismissed the cases as politically motivated.

Shahid Nawaz, a security official from Punjab province, confirmed the arrests, which include five parliamentarians. Authorities have also sealed off Islamabad using shipping containers and shut major routes connecting the city to PTI strongholds in Punjab and Khyber Pakhtunkhwa provinces.

Clashes erupted along highways bordering these provinces, with reports of teargas exchanges between police and PTI supporters. In response to escalating tensions, Pakistan suspended mobile and internet services in "areas with security concerns," though the government did not specify the locations or duration of the blackout.

Despite the crackdown, PTI members gathered in Peshawar in a festive mood, dancing, drumming, and displaying pictures of Khan as convoys departed for Islamabad. PTI spokesperson Sheikh Waqas Akram noted that Khan’s wife, Bushra Bibi, was traveling to the capital in a convoy led by Khyber Pakhtunkhwa’s chief minister, Ali Amin Gandapur.

Interior Minister Mohsin Naqvi announced that Islamabad’s Red Zone, home to key government buildings, had been sealed off, warning that anyone attempting to enter the area would face arrest. He accused PTI of disrupting daily life and blamed the protests for inconveniencing residents and businesses.

Naqvi also denied a full suspension of cellphone services, clarifying that only mobile data had been affected. However, reports from internet advocacy group NetBlocks highlighted disruptions to platforms like WhatsApp, hindering media sharing and communication.

The unrest comes just ahead of a visit by Belarusian President Alexander Lukashenko. Authorities claim security measures were intensified to prevent disruptions to the delegation’s itinerary.

The U.S. Embassy in Islamabad has issued a security alert, urging Americans in the area to avoid large gatherings, citing the potential for peaceful protests to escalate into violence.

This crackdown follows a pattern of stringent measures against PTI rallies, including a previous suspension of cellphone services in Islamabad and Rawalpindi, which disrupted essential services like banking and ride-hailing apps. As tensions rise, the government remains firm in its efforts to curtail pro-Khan demonstrations.