Former cricket champion Imran Khan, 65, is currently on course to become the country’s next prime minister with his Pakistan Tehreek-i-Insaf (PTI) party.
Based on 48 percent of counted votes from polling stations, PTI are leading the provisional results in 113 of 272 National Assembly constituencies.
Counting overnight was interrupted by glitches in an electronic tallying system, meaning the rest of the results are now being counted manually.
Opposition Pakistan Muslim League-Nawaz (PML-N) party, led by the brother of jailed ex-Prime Minister Nawaz Sharif, has already cried foul after winning just 64 constituencies.
The party tweeted several pictures of vote count ballots with the hashtag #MassiveRigging.
The rhetoric follows allegations women were barred from voting at several polling stations yesterday by military guards, who are said to back Mr Khan.
Around 371,000 soldier lined polling stations as a result of ongoing violence surrounding the election, with one suicide bombing by Islamic State killing 31 people yesterday.
When will the results be announced?
Chief Election Commissioner Sardar Mohammad Raza has denied the accusations saying “elections were 100 percent transparent and fair”, but could not set an exact deadline when the full results would be released.
But unofficial results, according to Pakistan’s Dawn newspaper, show PTI enjoy a clear lead.
His supporters have taken this as a sign of his win, cheering and waving flags on the streets in Karachi and Lahore.
Mr Khan’s spokesman Naeemul Hague tweeted his leader will “address the nation” at 2pm local time (10am BST) “in celebration and recognition of the massive support received from the people of Pakistan in the 2018 elections which was a contest between the forces of good and evil”.
Jemima Goldsmith has also tweeted her congratulations of her ex-husband’s ‘win’.
She wrote: “22 years later, after humiliations, hurdles and sacrifices, my sons’ father is Pakistan’s next PM. It’s an incredible lesson in tenacity, belief & refusal to accept defeat.
“The challenge now is to remember why he entered politics in the 1st place. Congratulations @ImranKhanPTI.”
Why is the election so controversial?
The election is historic as it is the second time in Pakistan’s 71-year history a civilian government has been handed power.
Mr Khan has been running on a populist vote to increase standards for millions of impoverished Muslims.
The nation of 208 million people has illiteracy rates in excess of 40 percent.
Socialite Mr Khan has continually denied he has the backing of the military, which influences heavily from the sidelines.
Even if he fails to secure an outright majority, he is likely to easily form a coalition with Benazir Bhutto, 29, and the Pakistan People’s Party (PPP).