Lawyers for former Pakistan Prime Minister Imran Khan filed an appeal on Tuesday against his conviction for graft, as he is incarcerated in a century-old prison at the beginning of a three-year term.

Unless overturned, the conviction will rule him out of contesting upcoming elections.

Pakistan's election commission on Tuesday issued a statement officially disqualifying Khan for five years.

He is being held at a colonial-era prison on the outskirts of historical Attock city, around 60 kilometres (40 miles) west of the capital Islamabad.

"We've submitted an appeal... our plea requests a temporary suspension of the trial court's ruling and seeks bail," Khan's lawyer Gohar Khan told AFP.

"The court will take up the case tomorrow and because the sentence is short we hope that Imran Khan will be granted bail in (several) weeks' time."

Power of attorney allowed Khan's legal team to file a bail application on his behalf Tuesday, and also appeal for him to be moved to a more comfortable "A-class cell", usually reserved for VIP inmates.

At a court hearing that Khan did not attend on Saturday, a judge found him guilty of failing to properly declare gifts he received while in office and sentenced him to three years in jail.

Parliament to be dissolved

Parliament will be dissolved on Wednesday - days ahead of the end of its natural term - meaning an election must be held by mid-November.

But the release of the latest census data at the weekend also means the election commission must redraw constituency boundaries, which the law minister said late Monday would likely mean a delay.

"God willing the matter will not go beyond 50 to 60 days," Azam Nazeer Tarar said on TV.

Khan's arrest and detention for three days in connection with the same case in May sparked deadly violence, with his supporters taking to the streets in the tens of thousands and clashing with police.