At least 89 people were killed and dozens others injured when two bomb blasts hit election rallies in Khyber Pakhtunkhwa and Balochistan provinces.
Terrorist group Daesh claimed responsibility for the deadly attack in Balochistan.
In the first incident near the KP town of Bannu, four people were killed and 39 injured when a bomb hidden inside a motorcycle detonated as a politician's convoy passed by on Friday, police said.
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The bomb targeted the convoy of the Muttahida Majlis-e-Amal (MMA) candidate Akram Khan Durrani, who survived the attack, police said.
"The bomb was planted in a motorcycle," regional police officer Kareem Khan said.
The MMA is a coalition of religious parties based in Pakistan's northwest. Durrani is standing against cricketer-turned-politician Imran Khan, whose Pakistan Tehreek-e-Insaf party (PTI) is one of the frontrunners in the July 25 vote.
"Strongly condemn the terrorist attack on Akram Durrani and his convoy," Khan tweeted after the attack. "There seems to be a conspiracy to sabotage the 25 July elections but the people of Pakistan will not allow any design intended to target these historic elections to succeed," he continued. Second bomb killed at least 85 people and injured 120 on Friday during an election rally in Mastung town, near the Balochistan capital of Quetta. The bombing was the biggest attack in Pakistan in over a year and is the third incident of election-related violence this week. Balochistan caretaker Health Minister Faiz Kakar told Reuters that the death toll had risen to 85 people, with over 120 wounded.
Provincial caretaker home minister Agha Umar Bungalzai also confirmed the explosion killed Siraj Raisani, who was running for a provincial seat with Balochistan Awami Party (BAP). "Mir Siraj Raisani succumbed to wounds while he was being shifted to Quetta," he added.
Raisani was younger brother of former provincial chief minister Mir Aslam Raisani.
Days earlier a bomb claimed by the Pakistani Taleban targeted a rally by the Awami National Party (ANP) in the city of Peshawar on Tuesday. Hospital officials said on Friday that the toll in that attack had risen to 22.