KABUL: Voting began on Saturday to elect a president for Afghanistan with more than 9 million Afghan registered voters potentially heading to the polls amid attacks in several cities.

Fourteen candidates are registered but the race will likely come down to incumbent President Ashraf Ghani and his former deputy Abdullah Abdullah. The winner will play a crucial role in the country's quest to end the war with the Taliban and the resumption of talks between the insurgents and the United States that were called off earlier this month.

The hardline insurgent group, which controls more of the country than at any time since its regime was toppled in 2001, has threatened voters to stay away from the election or face dire consequences.

To protect voters and polling stations from Taliban attacks tens of thousands of Afghan forces were deployed across 34 provinces.

About 9.6 million of Afghanistan's 34 million people are registered to vote for one of the 14 candidates at around 5,000 polling centres that will be protected by some 100,000 Afghan forces with air support from U.S. forces.

"Bravado gets defined when one musters the courage to cast their vote in Afghanistan," said Roya Jahangir, a doctor based in the capital of Kabul.

Jahangir said she and her husband will cast their votes even if it means standing in long queues for hours.

"We hope this time there is no fraud -- otherwise voters will feel cheated once again."

Media showed lines of men and women outside numerous polling stations, indicating strong turnout in some areas.

In the northern province of Balkh, voters waited for election officials to arrive at polling stations set up in schools, colleges, mosques, hospital campuses and district centres.

An explosion inside a polling station in the southern Afghan city of Kandahar was confirmed by local officials, as witnesses said an ambulance rushed to the area.

Bahir Ahmadi, a spokesman for Kandahar's provincial governor, confirmed the explosion and said so far three wounded had been transferred to the hospital.

Explosions also hit the Afghan cities of Kabul, Ghazni and Jalalabad, officials said.

POLLING STATIONS CLOSED

More than 400 polling centres will remain closed because they are situated in areas under Taliban control. Hundreds more will be closed because of security concerns.

The voting process is another source of concern. The country's Independent Election Commission (IEC) has come under criticism for issuing contradictory and unclear statements over what processes will be in place to prevent fraud if biometric systems fail during the eight hours of voting.

Four of the 18 candidates registered to contest for the top job have dropped out of the race, but their names remain on the biometric voting devices.

Chief contenders Ghani and his former deputy Abdullah both came to power in 2014 after a bitterly contested election marred by fraud.

Afghanistan’s political scene is still tainted by the aftermath of that disputed presidential vote which forced the two main rival groupings to form an unstable partnership. Both sides were accused of massive electoral cheating.

The Taliban claimed to have attacked several voting stations in Kunar, Ghazni, Paktia and Parwan provinces, but the reports could not be immediately confirmed.

Western security sources and Afghan officials said they had asked local media not to sensationalise threats and attacks, concerned that they could discourage voting.

The election is the fourth presidential vote since the fall of the Taliban to US-led forces.