KABUL (AFP) - The United States and the UN have praised the "courage" of Afghan people who turned out in force for presidential elections, despite Taleban threats against the vote which passed off largely peacefully.
Afghan voters formed long lines outside polling stations on Saturday to pick a successor to President Hamid Karzai, with a final turnout expected to exceed 50 percent - outstripping expectations.
US President Barack Obama congratulated the nation on the ballot - its first democratic transfer of power - and said it was "critical" to its future and securing continued international aid.
"Millions of Afghan men and women took to the polls today with courage and commitment," US Secretary of State John Kerry said in a statement.
"This is their moment. The Afghan people secured this election. They ran this election, and most importantly, they voted in this election."
There were no major militant attacks during polling, and organisers described the ballot as a huge success, despite complaints that a shortage of ballot papers had denied some citizens the right to vote.
However, with results not due until April 24 the country faces a testing period, 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 percent in the first round, a run-off is scheduled for late May.
There is no clear favourite among the front-runners to succeed Karzai - former foreign minister Zalmai Rassoul, Abdullah Abdullah, who was runner-up in the 2009 election, and former World Bank academic Ashraf Ghani.
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.
"Today's election and massive participation of the people have taken Afghanistan a few steps forward to peace, stability and development," Mr Karzai said in an address to the nation Saturday.
"This was a major effort of the people, our security forces, and all the officials who had a role in holding the election."
The United Nations Security Council also commended "the participation and courage of the Afghan people to cast their ballot despite the threat and intimidation by the Taliban" and other terrorist groups.
It condemned the deadly attacks which overshadowed the election campaign and urged all those involved to show patience and respect during the count.
Nato chief Anders Fogh Rasmussen praised the "enthusiasm" of voters and the "outstanding job" by Afghan security forces.
"This has truly been an election led by Afghans, secured by Afghans, for the future of Afghans," he said.
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.
The open nature of the race with so many candidates in the running, coupled with a massive security operation to thwart Taliban attacks, may have contributed to the high turnout.
The Taleban had urged their fighters to target polling staff, voters and security forces, but there were no major attacks reported during the day.
Interior Minister Omar Daudzai said late Saturday that four civilians, nine police and seven soldiers had been killed in violence in the past 24 hours, but added that many attacks had been foiled, without giving further details.
Attacks or fear of Taliban intimidation had forced more than 200 of a total 6,423 voting centres to remain closed.
The day before the poll, Associated Press photographer Anja Niedringhaus was shot dead by a police commander in eastern Khost province.
She was the third journalist working for international media to be killed during the election campaign, after Swedish journalist Nils Horner and Sardar Ahmad of Agence France-Presse.
Afghans have taken over responsibility for security from US-led forces, and this year the last of the Nato coalition's 51,000 combat troops will pull out, leaving local forces to battle the resilient Taleban insurgency without their help.
The country's third presidential election will bring an end to 13 years of rule by Mr Karzai, who has held power since the Taliban were ousted in 2001.
Massive fraud and widespread violence marred Mr Karzai's re-election in 2009, and a disputed result this time would add to the challenges facing the new president.
The election may offer a chance for Afghanistan to improve relations with the United States, its principal donor, after the mercurial Karzai years.
Relations fell to a new low late last year when Mr Karzai refused to sign a security agreement that would allow the US to keep around 10,000 troops in Afghanistan to train local forces and hunt Al-Qaeda.