A man was killed Tuesday when a bom he was planting in a polling both in Yemen's southern city of Aden went off, a security official said told AFP, a week ahead of presidential elections. "An unknown man trying to plant an explosive device in a polling booth in the neighbourhood of Crater... was killed when it exploded," the official said, on condition of anonymity. Security forces were swiftly deployed across Crater and near the election committees' headquarters. Activists from the Southern Movement who say the February 21 election failed to meet their aspirations for autonomy or southern independence, have been campaigning for a boycott of the election. Meanwhile, followers of extremist factions of the Southern Movement, led by Ali Salem Al-Baidh, openly called for actions to prevent the polls from taking place. The elections are taking place under a Gulf-brokered power transfer deal under which Yemeni President Ali Abdullah Saleh agreed to hand power to his deputy, Abd Rabbu Mansur Hadi, in return for immunity from prosecution for himself and his aides.