Nawaz Sharif is widely tipped to become Pakistan’s next prime minister in the country’s general election on May 11.
Polls have been placing two-time prime minister Sharif, and his Muslim League party, in the lead.
Former cricketer Imran Khan is also a contender. He was hospitalised on May 7 after he from a platform makeshift lift at a campaign rally.
Analysts said the injury could give him a big boost at the polls, and put a potentially serious dent in Sharif’s lead.
Khan is the favoured candidate of Pakistan’s powerful military, which ruled the country for more than half of its 66-year history.
The vote marks the first time a civilian government in Pakistan has completed a full five-year term.
In the troubled north-west of Pakistan, three people have been killed and more than 20 wounded by a blast at a police station in Bannu.
A suicide bomber drove a car packed with explosives into a barrier outside the building.