New Kyrgyz leader Almazbek Atambayev in unity pledge

media caption"History showed us that Kyrgystan will not tolerate an authoritarian regime", says Almazbek Atambayev

Newly-elected Kyrgyz President Almazbek Atambayev has said his biggest challenge will be to unify the country.

The overthrow of the last president 18 months ago was followed by deadly ethnic violence in the south, and the country remains deeply divided.

Speaking to the BBC, Mr Atambayev said he would punish those who stirred ethnic tensions.

And he said a key US military base should not stay in Kyrgyzstan after its lease runs out in 2014.

He said the Manas airbase - a logistics hub for the Afghan conflict - posed a threat to security.

"The US base should shut down. What if there is a war between the US and Iran and in response Iran bombs Manas? What will happen to us? I think in a civilian airport there should be no base."

Security, he said, was more important than financial or political gains associated with the base.

Mr Atambayev, who is backed by Moscow, said Russia was not pressuring him to shut the base down.

'Ethnic labels'

The new president, who served as prime minister under interim leader Roza Otunbayeva, said his key task was to bring the country together again.

More than 400 people were killed in fighting between Uzbek and Kyrgyz communities in the south of the country last year.

"I will never use ethnic labels - Uzbeks, Tatars, Kyrgyz," he said. "In my own family we have many nationalities. I just want to tell you that in the future people who ignite inter-ethnic and regional tensions will be punished."

With almost all ballots counted, election officials said Mr Atambayev had secured 63% of the vote.

His two main challengers each secured about 15% of the vote - the first since President Kurmanbek Bakiyev was ousted in popular protests in April 2010.

Observers from the Organisation for Security and Cooperation in Europe (OSCE) said irregularities overshadowed the vote, with reports of flawed voter lists, ballot-box stuffing and vote-buying.

"It is disappointing that the problems on election day meant that this election did not live up to the democratic promise resulting from the adoption of the new constitution," the OSCE's mission chief Corien Jonker said.

Mr Atambayev's closest rivals - Kamchibek Tashiyev and Adakhan Madumarov - say they plan to challenge the result.