Ex-Pakistan Prime Minister Imran Khan has called for nationwide protests after he was handed a three-year jail sentence over corruption allegations.
Mr Khan was found guilty of not declaring money earned from selling gifts he received in office. He denies the charges and says he will appeal.
After the verdict, Mr Khan was taken into custody from his home in Lahore.
In a pre-recorded statement posted after the verdict, he urged supporters to fight against the ruling.
"I have only one appeal, don't sit at home silently," he said in a video address posted to X, formerly known as Twitter. "I am struggling for you and the country and your children's future," he added.
The former cricketer-turned-politician, 70, was elected in 2018, but was ousted in a no-confidence vote last year after falling out with Pakistan's powerful military.
Mr Khan is facing more than 100 cases brought against him since his removal – charges he says are politically motivated.
However, the government has adamantly denied that there was any political motivation in Mr Khan's arrest or disqualification. Marriyum Aurangzeb, Pakistan's minister of information and broadcasting, told the BBC: "You have to be accountable for your deeds in law. This has nothing to do with politics. A person who has been proven guilty by the court has to be arrested."
Saturday's verdict centred on charges that Mr Khan incorrectly declared details of presents from foreign dignitaries and proceeds from their alleged sale.
The gifts – reported to be worth more than 140m Pakistani rupees ($635,000; £500,000) – included Rolex watches, a ring and a pair of cuff links.
"His dishonesty has been established beyond doubt," Judge Humayun Dilawar wrote in his ruling. Outside the courthouse, some pro-government demonstrators chanted "your show is over Khan".
Judge Dilawar said police had been instructed to arrest Mr Khan immediately. Within 15 minutes of the verdict, footage began to circulate on social media showing a line of police cars and trucks taking him away.
Imran Khan's lawyer, Intazar Hussain Panjutha, told the BBC the trial had been conducted by "a kangaroo-type court" in which "the accused was never given the opportunity to defend himself".
"As a consequence of today's conviction, he has been barred to take part in the politics for five years," Mr Panjutha said.
"But if the sentence and the conviction is suspended as we are hoping by the superior courts, he will then be able to come back to politics."
Mr Khan has been sent to Attock jail, a small facility in Punjab province with historical ties to the military, about 85km (52 miles) from the capital Islamabad. A number of members of Mr Khan's party have previously been held at the compound, local media reported.
For months he had avoided arrest, with his supporters at times fighting pitched battles with police to keep him out of custody.
In May, Mr Khan was arrested for not appearing at court as requested. He was then released, with the arrest declared illegal.
When he was last arrested on 9 May, there were protests across Pakistan. Thousands of his supporters arrested were alleged to have been involved in the protests.
Since then, Mr Khan and his political party have faced a dramatic crackdown, with many of his senior leadership arrested, before announcing they were leaving the party. Many vocal supporters of Mr Khan – who would previously post regularly about him on social media – now feel nervous to express their opinion or even have quietly deleted their previous comments.
Some of those arrested supporting Mr Khan will face trial in military courts, despite an outcry from many in human rights groups.
Indeed, several hours after Mr Khan's arrest, there had not been the kind of mass political protests seen in May. In Lahore, the BBC Urdu team saw some supporters who had gathered outside his home chanting and waving flags picked up by police. Around Islamabad, there's no evidence of increased security.
When questioned by BBC HARDTalk as to whether he had created an atmosphere of hostility to the military resulting in violence, Mr Khan said he and his party had never advocated the use of violence and had a record of peaceful protest.
Mr Khan said the army in Pakistan was "petrified" of elections which his party would win "hands down" and, for that reason, "they're dismantling a democracy".
Pakistan's army plays a prominent role in politics, sometimes seizing power in military coups and, on other occasions, pulling levers behind the scenes.
Many analysts believe Mr Khan's election win in 2018 happened with the help of the military.
In opposition, he has been one of its most vocal critics, and analysts say the army's popularity has fallen.
Since being ousted, Mr Khan has been campaigning for early elections, but Saturday's ruling means he will be disqualified from running in the much anticipated poll.
Ms Aurangzeb insisted that there was "no correlation" between Saturday's ruling and he prospect of elections.
"Just because there are elections down the road doesn't mean that you can't arrest him," she told the BBC. She accused Mr Khan of sidestepping and evading the law.
Pakistan's parliament will be dissolved on August 9, leaving a caretaker government to take over in the run up to the elections.
No election date has been announced, although constitutionally they should take place by early November.
However, on Saturday the country's law minister said the new elections would have to take place after the results of a new census were implemented.
Azam Nazeer Tarar told Geo News TV that it could take about four months to produce new constituency boundaries based from the count, potentially delaying the election by several months.
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