KABUL (AFP) - Afghans celebrated a largely peaceful election on Saturday, as turnout exceeded predictions despite Taliban threats to disrupt the vote to choose President Hamid Karzai's successor.

Long queues of voters waited throughout the day outside many of the 6,400 polling centres before the prolonged process of counting began, with preliminary results not due until April 24.

Whoever emerges victorious must lead the fight against the Taliban without the help of US-led combat troops, and also strengthen an economy that currently relies on declining aid money.

The country faces a testing few months as it undergoes its first democratic transfer of power, and many Afghans fear a repeat of the fraud scandals that marred the last presidential election in 2009.

If no candidate wins more than 50 per cent in the first round, a run-off is scheduled for late May.

There were no major militant attacks during polling, and organisers described the election as a huge success, despite complaints that a shortages of ballot papers had denied some citizens the right to vote.

"Today's election and massive participation of the people have taken Afghanistan a few steps forward to peace, stability and development," Karzai said in an address to the nation.

"This was a major effort of the people, our security forces, and all the officials who had a role in holding the election." The final turnout could exceed seven million, the head of the Independent Election Commission (IEC), Ahmad Yusuf Nuristani, said, though this was a preliminary estimate and may change. Initial predictions in 2009 proved inaccurate.

Around 13.5 million people were eligible to vote, putting the estimated turnout above 50 percent - a significant increase on 2009, when only around a third of voters cast ballots.