Sporadic attacks hit Afghan towns as polls opened on Thursday for an anxiously awaited presidential election that Taliban fighters have vowed to disrupt, but the United Nations said the turnout was encouraging, Reuters reported. "The vast majority of polling stations have been able to open and have received voting materials," said Aleem Siddique, spokesman for the U.N. mission in Kabul. "There have been a number of attacks, particularly in the south and east of the country. But we are seeing queues forming at polling stations in the north, also in the capital, as well as, encouragingly, in the east." Shops and businesses were closed and around-the-clock squads of extra police checked the few cars on the streets in Kabul. President Hamid Karzai was one of the first to vote in an election which could prove the toughest test yet of his own mandate and his nation's fragile democracy. He cast his ballot under tight security in a polling station at a high school near his presidential palace in Kabul, telling reporters he hoped for an outright majority in a single round. "One round will be in the interest of the nation," he said. Karzai faces an unexpectedly strong challenge from his former foreign minister, Abdullah Abdullah. Polls show Karzai winning by a strong margin, but possibly falling short of an outright majority and a second round run-off likely in October.Official preliminary results are not expected for at least two weeks. -- SPA