Pakistan's former prime minister Imran Khan challenged his conviction on graft charges in a high court on Tuesday, his lawyer said.
Naeem Panjutha said the petition to challenge the weekend conviction had been filed in the Islamabad High Court.
Khan has been jailed for three years on charges of selling state gifts unlawfully during his tenure as premier from 2018 to 2022.
Under a set procedure, the court has to admit the petition and then fix it for the hearing to start formal proceedings into the grounds cited by Khan's lawyer to overturn the conviction.
Khan, 70, has been at the heart of political turmoil since he was ousted as prime minister in a vote of no confidence last year, raising concern about stability in the nuclear-armed country as it grapples with an economic crisis.
"Being aggrieved and dissatisfied," Khan has appealed to the high court to "set aside" the trial court's order that convicted and sentenced him, according to a copy of the petition posted by Panjutha on social media platform X, formerly Twitter.
The former premier has been detained at a distant prison which according to his lawyers lacks facilities entitled to political prisoners.
Police took Khan from his home in the city of Lahore on Saturday and transferred him to the jail in Attock district, near the capital Islamabad.