WASHINGTON: Western powers hailed landmark elections in Afghanistan Thursday as a victory for democracy despite reports of a low turnout amid fears of Taliban retribution.

"We had what appears to be a successful election in Afghanistan despite the Taliban's efforts to disrupt it," US President Barack Obama said in a White House radio interview.

Obama's spokesman paid tribute to brave Afghans who defied fears of Taliban attacks to turn out and vote in presidential and provincial elections expected to return the Western-backed incumbent Hamid Karzai to power.

"Lots of people have defied threats of violence and terror to express their thoughts about the next government for the people of Afghanistan," White House spokesman Robert Gibbs said.

NATO Secretary General Anders Fogh Rasmussen described the polls, only the second time Afghanistan has voted for a president, as "testimony to the determination of the Afghan people to build democracy."

"I want to congratulate the people of Afghanistan for the courage they have shown in spite of challenging circumstances. We have seen Afghans defying threats of intimidation and violence to exercise their democratic rights."

The Taliban tried to cast a pall over the elections, which also saw 420 councillors chosen in 34 provinces across the country, by launching a series of high-profile attacks in the lead-up to the vote.

But voting day itself saw only sporadic Taliban violence, although some observers expressed fears of a low turnout especially in the south where the insurgency is bloodiest.

State Department spokesman P.J. Crowley said it was too early for the United States to pass judgment on the Afghan election's credibility.

"We expected that insurgents would try to intimidate the election process.

And we're pleased and we admire and respect the courage that Afghans showed in coming out to vote today," Crowley told reporters.

"But let's wait and see what results come in. It will be up to the Afghan people to judge whether this was a legitimate result."

British Foreign Secretary David Miliband and NATO's Rasmussen were full of praise for the Afghan forces who worked with international troops to provide security for the elections.

"Insurgents have tried hard, including through murderous attacks on ordinary civilians and international and Afghan troops, to disrupt these elections and prevent Afghans having their voices heard," Miliband said in a statement.

"Afghan National Security Forces, with international support, have performed strongly -- ensuring violence did not make the elections impossible. I pay tribute to the courage and professionalism of our own forces in all they have done to support this effort."

Britain's 9,100-strong force has suffered heavy losses in clashes with insurgents over recent weeks and seen its death toll in Afghanistan since the US-led invasion in 2001 soar past 200.

Canadian Prime Minister Stephen Harper admitted the polls had been "messy" but said this did not take away from the achievement.

"The Afghan election, for all its warts... was remarkable," Harper told reporters. "We always know the democratic process, even in this country, can be messy from time to time.

"When you look at a country that had virtually 30 years of civil war without any real history of democratic governance, what is taking place in Afghanistan, despite all its challenges, is remarkable."

UN chief Ban Ki-moon congratulated the Afghan people for voting despite the challenging security environment.

"By exercising their constitutional right to vote, the Afghan people have demonstrated again their desire for stability and development in their country," he said in a statement.

Spain, which has around 1,230 soldiers in the NATO-led International Security Assistance Force in Afghanistan, described the election as "an expression of the will and the maturity of the Afghan people."

Around 300,000 security forces personnel, a third of them NATO and US-led troops, were deployed to protect polling after the Taliban threatened attacks.

Results were not expected until September and turnout alone will not be known for several days -- the figure is expected to be well down on the 70 percent achieved in Afghanistan's first presidential election five years ago.