A leading contender for the Kyrgyzstan presidency, along with a third of the other candidates, has said he will reject the outcome of Sunday's election.
"Tens of thousands of voters couldn't vote in line with their constitutional rights. They are outraged," said Adakhan Madumarov, one of two serious challengers to the Moscow-backed Prime Minister Almazbek Atambayev.
The central election commission said preliminary data showed more than 57 per cent of voters had turned out for the election.
But less than an hour before polls closed, six out of the sixteen presidential candidates declared the vote unfair, saying that it had been marred by multiple voting and poorly prepared lists that had excluded many from the ballot.
"We want an honest president who can uphold the law, somebody who will not allow the country to be divided by clans or by north and south."
- Aida, 43, schoolteacher
The vote comes 18 months after a popular uprising and ethnic unrest, which left hundreds of people dead.
A clean election would signal the first peaceful handover of the presidency in the mainly Muslim country after 20 years of failed authoritarian rule, the culmination of reforms set in motion after a bloody revolt toppled the president last year.
Instability in Kyrgyzstan worries the US and Russia, which both operate military air bases in the country of 5.5 million people and share concerns over drug trafficking and the possible spillover of Islamist violence from Afghanistan.
"We want an honest president who can uphold the law, somebody who will not allow the country to be divided by clans or by north and south," said Aida, a 43-year-old schoolteacher who declined to give her surname.
No 'absolute power'
Those who took power after the April 2010 revolution, led by outgoing President Roza Otunbayeva, have watered down the powers of the president and established parliament as the main decision-making body in Kyrgyzstan.
"A parliamentary system is more suited to the nomadic spirit of the people," Atambayev, the pro-free-market prime minister who is the flagbearer of the reforms, told reporters after casting his vote.
"After 20 years, we are convinced that we don't need absolute power, which can transform itself into dictatorship."
Opinion polls have made 55-year-old Atambayev the clear favourite.
"He's a grafter," said retired construction worker Nikolai Dubovik, 77, who braved the first snow of winter to vote early at a school in the capital Bishkek.
But analysts question whether he can secure the outright majority required at the first attempt. If he falls short, he will face a strong challenger from the south in a run-off.
Per capita GDP in Kyrgyzstan, at below $1,000, is less than a tenth of that in its oil-rich neighbour Kazakhstan. The economy relies heavily on remittances from migrant workers and the production of a single gold mine.