The arrest and jailing of Imran Khan has triggered uproar in Pakistan after a court convicted the former prime minister in the so-called Toshakhana case on Saturday.
A district and sessions court in Islamabad found Khan guilty of fraudulent practices involving the state gift depository.
Additional and Sessions Judge Humayun Dilawar rejected Khan's appeal for inadmissibility of the case and sentenced him to three years in prison.
Khan, 70, chairman of Pakistan Tehreek-e-Insaf (PTI), was arrested at his home in Zaman Park, Lahore.
He was found guilty of exploiting his position as prime minister to buy and sell gifts which were obtained for the Toshakhana, a Cabinet body that deals with such offerings to the government, during foreign tours. They were valued at more 140 million Pakistani rupees ($635,000).
PTI activists took to the streets in parts of the country in protest against the court's decision. In Lahore, they gathered outside Khan's house.
PTI central leader and former politician Shaukat Yousafzai told The National that the court's decision was unlawful.
“If we see the history of Toshakhana, every prime minister and government has taken gifts from it. How can the incumbent government punish Imran Khan for this,” he said.
Mr Yousafzai claimed that even if Khan was arrested and imprisoned, people would still vote for his party.
“The continuing price hike [cost of living rises] has badly disturbed the masses and the incumbent rulers are bound to lose coming elections,” he said.
“We, the PTI, also appeal to the international community to ensure fair elections in Pakistan. This will prove the real contest and real popularity of political leaders as to which one comes into power as a result of the balloting.”
In Peshawar, the city where Khan's political popularity began to flourish, PTI activists blocked GT Road, the main route of the city, creating problems for commuters.
Party supporters also started protests in Punjab, Khyber Pakhtunkhwa, and other parts of the country.
Ikhtiiyar Wali, a leader of Pakistan Muslim League-N party and a former politician, said that he and his party welcomed the court's decision, adding that everyone should obey the law.
“During his time in government, Imran doubled Pakistan's debts, which was around 25,000 billion rupees at the start of his government and reached around 50,000 billion rupees in his rule, after he had been imposed on the country by the security establishment,” Mr Wali said.