The audio clip, marred by internet disruptions, was played over the AI-generated image which appears to be speaking, during an internet rally of Khan's Pakistan Tehreek-e-Insaf party on Monday.
It drew more than 1.4 million views on YouTube and was attended live by tens of thousands on other social media platforms.
Join PTI's first virtual powershow: — Imran Khan (@ImranKhanPTI) https://t.co/ys0JHq9LvwDecember 17, 2023
"Our party is not allowed to hold public rallies," Khan said in the clip, urging supporters to turn out in large numbers at general elections set for February 8.
"Our people are being kidnapped and their families are being harassed."
The disruptions to live streaming fuelled transparency concerns about the upcoming elections, with users nationwide complaining of slow internet speeds and throttling, a technique telecoms regulators use to choke streaming on apps.
Pakistan's telecoms regulator said the interruptions were being investigated but that internet accessibility overall appeared to be normal.
Khan's speech was generated from a written version he had approved from prison, said officials of his party, which staged the event because it faces a state-backed crackdown on physical gatherings while its leader is blacked out of media.
Jailed since he was convicted and sentenced to three years on graft charges on August 5, Khan is embroiled in dozens of court cases, with some trials held in prison behind closed doors, which legal experts say infringes his right to fair proceedings.
Pakistan's former prime minister Imran Khan (centre) has been jailed since August 5. (AP PHOTO)
Murtaza Solangi - information minister in Pakistan's caretaker government assigned to supervise the elections but suspected of favouring Khan's opponents - said the query on internet disruptions could be referred to the telecom regulator or the ministry of information technology.
"I have no information about it," he said.
However, he did not respond when asked whether it was a violation of free speech and assembly mandated by election laws for free and fair voting, which in this case could be a pre-poll rigging.
A political crisis has swirled around the 71-year-old former cricket star since his ouster last year as prime minister in a vote of confidence in parliament.
The party crackdown followed a May assault on military sites by supporters protesting his brief arrest.
Khan won the last general election in 2018, a victory his opponents said was achieved with help from the military, which often plays an outsized role in making or breaking governments in Pakistan.
Khan also blames his removal on the military after a falling-out with generals over the appointment of the chief of Pakistan's main spy agency.
The military denies Khan's claims.
