Pakistani police arrested Fawad Chaudhry, the vice president of Pakistan Tehreek-e-Insaf party, on Wednesday on charges of threatening the chief of the elections overseeing body and other government officials.
The arrest is seen as a major setback for the party and has been condemned by Imran Khan, the former Prime Minister, who claimed that it left no doubt that Pakistan has become a place "devoid of rule of law".
Pakistan Tehreek-e-Insaf party has also demanded the release of Chaudhry.
In his tweet, Imran Khan expressed his concerns about the arrest of Chaudhry and urged his followers to defend their fundamental rights to prevent the country from falling towards a point of no return.
The Pakistani government has been criticised for cracking down on opposition parties and leaders, particularly ahead of the upcoming elections.
The arrest of Chaudhry is believed to be a part of these efforts.
Pakistan's Human Rights Commission has voiced concerns over the situation, saying that the government's actions could undermine democratic values in the country.
While the government has defended its actions, saying that they are necessary to maintain law and order, opposition parties have accused it of violating human rights and freedom of speech.