The state of emergency and imposition of a new governor in Khyber Pakhtunkhwa sharply escalates a standoff between Khan's Pakistan Tehreek-e-Insaf (PTI) party and the government, and comes a week after PTI supporters gathered in the province intending to march on Islamabad to demand Khan's release.
The party's last large-scale protest two years ago ended in deadly clashes with security forces and Khan's 2023 arrest sparked nationwide riots that threatened the military's standing.
Hundreds of activists and three of Khan's sisters have been detained ahead of the planned march, in what the PTI called one of the strongest crackdowns in years.
Pakistan's constitution allows the government to take over from provincial authorities during an emergency, and Law Minister Azam Nazeer Tarar said a provincial governor would take charge in Khyber Pakhtunkhwa, which has suffered an increasing number of militant attacks in recent months.
Tarar told a news conference in Islamabad on Sunday that the governor would initially be in place for six months, but could stay for as long as needed. The interior ministry said it would be deploying troops in the province.
The federal government and the military accuse PTI of failing to curb militants. The party rejects the charge and says Islamabad has not provided the funding and equipment it needs.
Restrictions have been placed on the movements of Sohail Afridi, who had previously been in charge of the province, one of his close aides told Reuters.
Khan's aide and PTI spokesperson Zulfikar Bukhari called the government's move "more of a coup disguised as emergency", adding that it risks leading to further bloodshed and instability and was intended to stop the protest.
The government has expanded the military's powers and PTI accuses the army of dominating politics, which the military denies.
Maulana Fazlur Rehman, leader of the JUI-F political party and engaged by the government to mediate with PTI, also condemned the move.
"Imposition of emergency is an ambush on democracy," he told a news conference in Islamabad.
The government has deployed tens of thousands of security forces in Islamabad and lined roads with containers ready to block roads, to bar protesters from reaching parliament.
Candidates backed by Khan's party won the most seats in the 2024 election but formed a government only in Khyber Pakhtunkhwa. Supporters of the 74-year-old former cricket star say the military rigged the vote against him, which the military denies.
Cases against Khan range from concerns over state gifts to instigating violence and an accusation of an unlawful marriage. All but one conviction have been suspended or overturned, with appeals pending. He denies wrongdoing.
President Asif Ali Zardari declared the emergency on the advice of Prime Minister Shehbaz Sharif after a cabinet decision.
Sharif told the cabinet that security forces and citizens had been under attack for two years.
"We can't just act as a silent spectator."
Islamabad also accuses Afghanistan of harbouring militants who launch attacks inside Pakistan, and says PTI has sympathised with the Taliban in Kabul and its domestic affiliates.
