Voting begins in Afghan presidential runoff amid tight security

Voting is underway in Afghanistan's presidential runoff amid tight security following warnings from the Taliban.

Ahmad Yousuf Nuristani, the head of the election commission, officially opened Saturday's runoff at 7 a.m. local time (0230 GMT) by casting his vote. He called on all people to take part in the election, and to come out early rather than waiting until the end of the day.

The runoff is between former foreign minister Abdullah Abdullah and ex-World Bank official and former finance minister Ashraf Ghani Ahmadzai, after neither secured the 50 percent margin needed to win in the first round on April 5.

Afghanistan's next president will succeed Hamid Karzai and preside over the withdrawal of most foreign troops by the end of the year.