Kabul, Aug 20 (DPA) Amid tight security and militant threats to disrupt polls, the presidential and provincial elections began nationwide Thursday with around 17 million Afghans eligible to vote. President Hamid Karzai cast his vote at a polling station near the presidential palace early in the day.

Karzai is vying for re-election against about 30 candidates including two women. The election is the second direct vote for president in the recent history of Afghanistan.

Former foreign minister Abdullah Abdullah, former finance minister Ashraf Ghani and former planning minister Ramazan Bashardost are the main challengers to the incumbent. All three served in Karzai's government in the past.

Polling stations opened at 7 a.m. (0230 GMT) and voting is to continue until 4 p.m. (1130 GMT), while initial results are expected about 48 hours after the polls close, according to the Independent Election Commission.

Initial turnout was about three to four times lower than in the 2004 elections, possibly also out of fear of attacks, which in Kabul often occur in the early hours of the day, witnesses said.

People were afraid of attacks, but there was hope that turnout would pick up later in the day, political analyst Haroon Mir told DPA.