The Pakistan Tehreek-e-Insaf (PTI) on Tuesday claimed that party chairman Imran Khan was grabbed by the neck and abducted by the Rangers.
The former Pakistan cricket captain and Prime Minister was arrested outside Islamabad High Court by the Paramilitary force.
DG Rangers Major General Azhar Waqas ordered the arrest followed by the decision of the high command.
Imran Khan, who was appearing in court on charges of corruption which he says are politically motivated, travelled from Lahore to the federal capital Islamabad.
"Khan has been arrested in the Al-Qadeer trust case when he was present in the Islamabad High Court," his party said in a brief statement.
The arrest comes a day after the powerful army had accused Khan of levelling baseless allegations against a senior army officer.
The PTI alleged that Khan was being tortured but it was not confirmed independently.
"State terrorism - breaking into IHC premises to abduct Imran Khan from court premises. Law of the jungle in operation. Rangers beat the lawyers, used violence on Imran Khan and abducted him," tweeted former minister Shireen Mazari, a PTI spokeswoman.
Another PTI leader Azhar Mashwani alleged that Khan had been "abducted" from inside the court by the Rangers. He said that the party had given an immediate call for staging protests in the country.
"They are torturing Imran Khan right now [ ] they are beating Khan sahib. They have done something with Khan sahib," Cheema said in a video message posted on the party's Twitter handle.
