Bombers killed 20 people and wounded dozens more in Pakistan on Tuesday in the bloodiest day of violence yet on the campaign trail for next month\'s historic general election. Pakistan goes to the polls on May 11 for an election that will mark the first time a civilian government has handed over power at the ballot box after completing a full term in office, in a country used to extended periods of military rule. But campaign rallies have got off to a lacklustre start, in part dogged by security fears in the nuclear-armed nation troubled by Al-Qaeda-linked violence and where the Taliban have followed through on a series of threats against politicians. On Tuesday, Pakistan\'s umbrella Taliban faction claimed responsibility for a suicide attack that officials said killed 16 people and wounded dozens more at a rally attended by a former cabinet minister in the northwestern city of Peshawar.Senior Awami National Party (ANP) leader Ghulam Ahmed Bilour, who served as railways minister in the outgoing government, escaped the bombing with cuts and bruises. He appeared on television with blood spattered on his trousers. \"At least 16 people have died and more than 35 been wounded,\" Doctor Arshad Javed, chief of Peshawar\'s main Lady Reading hospital, told AFP. Officials had earlier said nine people were killed. Senior police official Shafqat Malik told AFP the attack was a suicide bombing. Ghulam, whose brother and ANP leader Bashir Bilour was assassinated by the Taliban last year, became an insurgents\' favourite after posting a $100,000 ransom for the death of a film-maker behind a controversial anti-Islam movie last year. The Taliban apologised for injuring Bilour, saying it had targeted his nephew, Haroon, the son of the slain ANP leader.The Taliban have directly threatened the ANP and its outgoing coalition partners, the Pakistan People\'s Party and the Muttahida Qaumi Movement, which are perceived as secular. Elsewhere, another bomb targeted the main opposition Pakistan Muslim League-N (PML-N) party, killing four people travelling in a campaign convoy in the southwestern province of Baluchistan. Sanaullah Zehri, head of the PML-N in Baluchistan, survived, but his son, brother, nephew and their guard were killed, officials said. \"An improvised explosive device went off as Zehri, leading a convoy of more than 20 vehicles, left his home to campaign,\" provincial official Akbar Durrani said. There was no claim of responsibility. Zehri survived a murder attempt two years ago that was claimed by the rebel Baluch Liberation Front.Tuesday\'s attacks bring to 24 the number of people killed in five deadly attacks targeting politicians or political parties across the country since last Thursday. In response, Pakistan\'s caretaker interim prime minister Mir Hazar Khan Khoso ordered the interior ministry to improve intelligence-sharing and step up coordination to avoid such incidents. The violence overshadowed the disqualification on Tuesday of former military ruler Pervez Musharraf from contesting the elections, crushing his ambition to \"save\" the troubled country just weeks after his return from exile. The retired general is on bail over the 2007 killing of former prime minister Benazir Bhutto and the 2006 death of a rebel leader from the region of Baluchistan, and for sacking judges when he imposed emergency rule in 2007. The Taliban threatened to assassinate him on the eve of his return to Pakistan on March 24, where he was welcomed by only a few hundred ardent supporters. The 69-year-old applied to run for parliament in four seats but a court official threw out the only seat he had been initially approved to contest on the grounds that he violated the constitution in 2007. Musharraf pledged to continue his mission and his team vowed to challenge the decision in the Supreme Court, which is also hearing a separate petition from lawyers demanding that he face trial for treason. \"The selection bias and unwarranted activism shown by the election tribunal in rejecting my nominations papers from all four constituencies is not going to deter my resolve to help save Pakistan,\" he said in a statement. Commentators said Musharraf was finished, given the hostility in the Supreme Court to the man who dismissed the current chief justice in 2007.