Imran Khan's son has called on Pakistani authorities to prove his father is alive, amid a block on prison visits and growing concerns about his health in jail.
His family, Khan's political party and his lawyers have said they have not been able to see him for more than three weeks.
They have all expressed concerns about his health, with the issue trending online in recent days.
Pakistan's former leader has been in jail since August 2023, serving a 14-year sentence on corruption charges.
It is one of dozens of cases he says are trumped up by the army to keep him out of politics, a charge the military denies.
Posting on X, Khan's son, Kasim Khan, wrote that his father had been under arrest for 845 days and "for the past six weeks, he has been kept in solitary confinement".
"This absolute blackout is not a security protocol. It is a deliberate attempt to hide his condition and prevent our family from knowing whether he is safe," Mr Khan wrote.
"Let it be clear: the Pakistani government and its handlers will be held fully accountable legally, morally and internationally for my father's safety and for every consequence of this inhumane isolation."
He called on governments and global human rights groups to intervene urgently and "demand proof of life, enforce court ordered access" and to "end his inhumane isolation".
[TWEET]Zulfikar Bukhari, spokesperson of Khan's Pakistan Tehreek-e-Insaf (PTI) party, said on Thursday that no reason had been given for not granting meetings.
Khan is being denied visits and medical support despite his status of a former prime minister.
"His health is our concern. We are worried about his illegal isolation," Mr Bukhari told Reuters.
'Where is Imran Khan?'
Khan's family and party members have protested outside the jail in the garrison city of Rawalpindi in recent days demanding a meeting.
A delegation from the party visited the prison to see Khan on Thursday, but authorities again denied access, Mr Bukhari said.
Prison rules allow Khan to meet outsiders at least once a week, although prison authorities can suspend such access.
There have been long gaps spanning weeks when Khan was not allowed to meet outsiders, the party said.
Local media reported that the 73-year-old former international cricketer might be moved to a high-security prison to make meeting him more challenging.
Khan's status has become a talking point on social media and #WHEREISIMRANKHAN was trending on X on Thursday.
Pakistan's interior ministry did not respond to a request for comment.
A jail official, speaking on condition of anonymity, told Reuters that the former premier was in good health, and that he was not aware of any plans to move him to any other facility.
Khan was elected prime minister in 2018 but was ousted in 2022 in a parliamentary vote after he fell out with military generals, who play a significant role in making or breaking governments in Pakistan.
His arrest in May 2023 sparked protests against the military nationwide, leading to a crackdown on the party.
The party emerged as the single biggest in the 2024 election, but says that rigging robbed it of more seats to help other parties form a coalition government under Prime Minister Shehbaz Sharif.
Mr Sharif and his allies deny the charges.
ABC/wires
