Pakistan's former Prime Minister Imran Khan was arrested Saturday at his home in Lahore after a judge found him guilty of graft and sentenced him to three years in jail.

"I have just received the information that Imran Khan has been arrested," Attaullah Tarar, special assistant to Prime Minister Shehbaz Sharif, told reporters.

Police in Lahore also confirmed that Khan was arrested by officers from the Islamabad force.

In a case concerning the illegal selling of state gifts, Khan, chairman of the former ruling party Pakistan Tehreek-e-Insaf (PTI), was sentenced by a local court in the Pakistani capital of Islamabad for hiding his financial assets.

The judge also disqualified Khan for five years from holding any office and imposed a fine of 100,000 rupees (around $355) on him – if it is not paid, he would have to spend six more months in jail.

The former prime minister was not present in court when the decision was announced.

In a statement, the PTI said it "rejected the biased decision of the biased judge" and announced it would challenge the decision before the Supreme Court.

Khan, in a pre-recorded message released after his arrest, called on his supporters to remain peaceful.

"My arrest was expected and I recorded this message before my arrest... I want my party workers to remain peaceful, steadfast and strong," he said in a video statement posted on social media.

(With input from agencies)