Authorities in Pakistan say a suicide bomb attack killed at least 13 people and injured at least 54 others in a blast at a political rally in the northwestern city of Peshawar on Tuesday. Haroon Bilour, a candidate for the Awami National Party (ANP), which has been the target of Islamist militants for its opposition to groups such as the Taliban, was killed in the attack.

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The attacker struck when Bilour was about to address some 200 supporters.

Haroon Bilour was the son of senior ANP politician Bashir Ahmed Bilour, who was killed in a 2012 suicide attack in Peshawar carried out by the Taliban Movement of Pakistan (TTP). Haroon Bilour's 16-year-old son Daniyal was among those seriously injured in Tuesday's attack.  

ANP leader Mian Iftikhar Hussain said the attack was aimed at derailing Pakistan's democratic system. While Chief Election Commissioner Sardar Muhammad Raza said: "This shows the weakness of our security institutions and a conspiracy against transparent elections."

Imran Khan, the chairman and presidential candidate of the Pakistan Movement for Justice party (PTI), took to Twitter to convey his condolences. He went on to "strongly condemn the terrorist attack" adding, "all candidates must be provided security during their election campaigns by the State."

Pakistan's general election will be held on Wednesday, July 25.