Militants threatening to kill three United Nations hostages including a woman from Northern Ireland said today that a noon deadline could be postponed for negotiations on demands that include the world body’s withdrawal from Afghanistan.

Investigators have clear evidence of ballot-stuffing in Afghanistan’s landmark presidential election but not on a scale that would overturn interim leader Hamid Karzai’s victory, according to a senior official.

Afghanistan’s interim leader, Hamid Karzai, held a 45% lead today in the preliminary results of the country’s first presidential election, though a chief rival said the validity of the vote was in doubt.