The raids in Islamabad come after large protests in the capital calling for Khan's release from jail.
Pakistani police have arrested several lawmakers and leaders from former Prime Minister Imran Khan's party in a series of raids in Islamabad, according to party officials and authorities.
A police spokesman said on Tuesday that four people were arrested, however, the Pakistan Tehreek-e-Insaf (PTI) put the number at 13, saying they were picked up from various locations in the capital Islamabad, including some outside parliament.
The raids followed a large PTI rally on Sunday demanding the release of the 71-year-old cricketer-turned-politician from jail, where he has been held for more than a year.
The crackdown began on Monday evening, with PTI Chairman Gohar Khan being detained.
Khan was ousted as prime minister in 2022 after a clash with military generals, who largely decide who will rule the nation of 241 million people.
Media footage showed police pushing lawmakers into vehicles in arrests outside parliament that Omar Ayub Khan, the opposition leader, called “despicable”.
“Yesterday's massive protest sent shivers down the spine of the government,” Khan's aide Zulfikar Bukhari said in a post on X, calling the arrests illegal.
Others arrested included senior leaders Shoaib Shaheen and Sher Afzal Marwat, added Bukhari, who is also a PTI spokesperson.
In February, PTI-backed candidates won a majority of seats in a general election, but fell short of the majority needed to form a government.
Instead, his rivals formed a coalition to establish a ruling alliance headed by Prime Minister Shehbaz Sharif.
They demand the release of Khan
The rally demanding Khan's release was marred by clashes between supporters and police that injured a senior police officer, police said.
The PTI said the violence broke out after police fired tear gas canisters at a peaceful gathering in an attempt to disperse it.
Some party leaders, including Chief Minister Ali Amin Gandapur of the northwestern province of Khyber Pakhtunkhwa, criticised the ruling alliance and the military's speeches at the rally.
“Put your houses in order,” he advised the army, warning against any attempt to prosecute Khan militarily. “I am not afraid of the military uniform.”
Information Minister Attaullah Tarar said Gandapur had threatened to forcibly release Khan from jail and incited his supporters to take part in violence.
In a statement on X, PTI said Khan thanked his supporters for holding the rally peacefully and quoted him as saying, “You all have broken the chains of fear to stand up and fight.”
