Party spokesman Zulfi Bukhari told Reuters the specific reason for the detention of Qureshi, twice Pakistan's foreign minister, was not immediately clear. The caretaker information minister did not immediately respond to a request for comment.

Bukhari condemned the arrest on the social media platform X, formerly known as Twitter, saying he was "arrested for doing a press conference and re affirming PTI stance against all tyranny and pre poll rigging that is going on currently in Pakistan".

PTI party chairman Imran Khan is currently jailed for three years after being convicted on graft charges and is barred from contesting any election for five years. He denies any wrongdoing. Khan won the last election in 2018 and became prime minister until he was ousted in a no-confidence vote in 2022.

The election is meant to be held within 90 days of parliament being dissolved last week, by November, but uncertainty looms over the date as the nation grapples with constitutional, political and economic crises.

The outgoing government approved a new census in its final days, meaning new electoral boundaries must be drawn up by the Election Commission.

The exercise of drawing fresh boundaries for hundreds of federal and provincial constituencies in a country of 241 million people may take six months or more, according to a former commission official.

IMF BAILOUT

The election commission said on Thursday that new constituencies would be finalised by Dec. 14, state television reported. After that, the commission will confirm an election date.

Electoral experts have suggested that process could see the nationwide vote pushed back several months, possibly until February.

"It will be unconstitutional if the 90 days deadline is breached," Qureshi, who is leading the Pakistan Tehreek-e-Insaf, following Khan’s arrest, told the press conference.

He said the party planned to contest any delay at the Supreme Court.

Political analysts say that if the current caretaker set-up stretches beyond its constitutional tenure, a prolonged period without an elected government would allow the military, which ruled the country directly for more than three decades of its 76-year existence, to consolidate control.

Anwaar-ul-Haq Kakar, a little-known politician who is believed to be close to the military, was sworn in as prime minister on Monday.

Caretakers are usually limited to overseeing elections, but Kakar's set-up is the most empowered in Pakistan's history thanks to legislation that allows it to make policy decisions on economic matters.

The move is ostensibly aimed at keeping on track a nine-month $3 billion International Monetary Fund bailout secured in June. At least one of three programme reviews falls during the caretaker period, and more if elections are delayed.