Supporters of Imran Khan were planning to march to Islamabad on Wednesday where the former Pakistan prime minister is in custody in a corruption case, raising fears of more clashes with security forces.
Mobile data services in the country were shut while Twitter, YouTube and Facebook were disrupted. Television carried watered-down coverage of violence that erupted on Tuesday.
Authorities in three of Pakistan's four provinces have imposed an emergency order banning all gatherings after Khan's supporters clashed with police.
Khan was arrested from the Islamabad High Court on Tuesday by Pakistan's anti-corruption agency. Police said a court hearing would take place at the police guest house where he is being held.
The arrest came a day after the country's powerful military rebuked Khan for repeatedly accusing a senior military officer of trying to engineer his assassination and the former armed forces chief of being behind his removal from power last year.
In response, his Pakistan Tehreek-e-Insaf (PTI) party called for a "shutdown" across the country, with Khan's supporters clashing with police in many cities and storming military buildings in Lahore and Rawalpindi, according to witnesses and videos shared by his party.
Supporters in northwestern Khyber Pakhtunkhwa province were asked to gather early on Wednesday in Swabi city to leave for Islamabad as part of a convoy, the party wrote on Twitter.
PTI Vice Chairman Shah Mahmood Qureshi said the party's senior leadership was in Islamabad to meet Khan and will approach the Supreme Court to challenge an Islamabad High Court order that deemed Khan's arrest legal.
"We continue to call PTI family workers, supporters and the people of Pakistan onto the streets for peaceful protest against this unconstitutional behaviour," Qureshi wrote on Twitter.
A police spokesman told Reuters on Wednesday that Khan will not be brought to court and his scheduled hearing will take place at the location where he is being held under custody in the Islamabad police lines area.
At least one person was killed on Tuesday and 12 others injured, including six police officers, in clashes in the southern city of Quetta, provincial home minister Ziaullah Langove said.
Khan, 70, a cricket hero-turned-politician, was ousted as prime minister in April 2022 in a parliamentary no-confidence vote. Khan has not slowed his campaign against the ouster even though he was wounded in a November attack on his convoy as he led a protest march to Islamabad calling for snap general elections.
His arrest comes at a time when Pakistanis are reeling from the worst economic crisis in decades, with record high inflation and anaemic growth. An International Monetary Fund bailout package has been delayed for months even though foreign exchange reserves are barely enough to cover a month's imports.
The corruption case is one of more than 100 registered against Khan since his ouster after four years in power. In most of the cases, Khan faces being barred from holding public office if convicted, with a national election scheduled for November.
Political infighting is common in Pakistan, where no prime minister has yet fulfilled a full term and where the military has ruled for nearly half of the country's history.