Pakistan's former prime minister Imran Khan has been arrested outside the High Court in the capital, Islamabad, APA reports citing BBC.
Mr Khan was appearing in court on charges of corruption, which he says are politically motivated.
Footage showed dozens of paramilitary forces in armoured vehicles detaining Mr Khan after he entered the court compound, then driving him away.
He was ousted as PM in April last year and has been campaigning for early elections since then.
General elections are due to be held later this year.
Mr Khan's Pakistan Tehreek-e-Insaf (PTI) party has called on its supporters to protest. In the hours since he was detained, violence has been reported from a number of cities including Lahore, Karachi and Peshawar.
On the streets of Islamabad, hundreds of protesters have blocked one of the main highways in and out of the capital.
People pulled down street signs and parts of over passes, lit fires and threw rocks. During the hour or so the BBC were there we saw no police or authorities.
Protestors said they were angry about Imran Khan's arrest.
"This is absolutely the last straw," said Farida Roedad
"What else can we do? What else is there left in Pakistan? We have never said a word against the army, I wish we had.
"Let there be anarchy, let there be chaos. If there is no Imran there's nothing left in Pakistan. No one is there to take over."
Former Pakistan Prime Minister Imran Khan has been arrested by paramilitary troops in Islamabad on charges brought by the country’s anti-corruption agency, APA reports citing CNN.