A motorbike bomb close to party political offices killed four people and wounded 15 in a town in Pakistan's restive tribal northwest Friday, on the eve of the country's general election. The bomb went off in the main bazaar of Miranshah, the main town in North Waziristan district, a notorious hub of Taliban and Al-Qaeda linked militants, a security official said. Pakistan goes to the polls on Saturday to elect a new government, the first time in the country's turbulent history that one civilian administration has handed power to another through the ballot box. But the campaign has been marred by violence, with more than 100 people killed in bombings and shootings in the month leading up to polling day, according to an AFP tally. Witnesses and hospital officials said 15 people had been taken to the state-run Miranshah hospital, some of them in a serious condition. Another official in the northwestern city of Peshawar confirmed the blast and the casualties. No one has claimed responsibility for the blast, but the Taliban, who consider election as un-Islamic, have carried out numerous attacks to undermine the polls. The Pakistani Taliban have directly threatened the secular leaning outgoing Pakistan People's Party and its main coalition partners, the Muttahida Qaumi Movement and the Awami National Party.