BISHKEK, KYRGYZSTAN (AFP) - Populist Sadyr Japarov was sworn in as president of ex-Soviet Kyrgyzstan on Thursday (Jan 28), completing a remarkable transformation from prisoner to president in the space of a few months.

Mr Japarov, 52, was serving jail time on hostage-taking charges before he was freed during a political crisis over a parliamentary vote in October, beginning a dizzying rise to the top of the leadership.

He won a Jan 10 presidential election by a landslide, with close to 80 per cent of the vote.

Mr Japarov on Thursday swore to "preserve the integrity of the people and the security of the country" as he placed his hand on the Kyrgyz Constitution, which is set to be overhauled in the coming months.

Voters chose a presidential form of government over a parliamentary model in a referendum held in parallel to the presidential vote.

A Kyrgyz Cabinet official said on Monday that Mr Japarov would make his first foreign trip as president to Russia, where hundreds of thousands of Kyrgyz live and work.

Moscow has taken a dim view of political upheavals in the mountainous country of 6.5 million that looks to next-door China for loans and investment.

The new Constitution is likely to grant the head of state sweeping new powers when it is passed and reverse the single-term limit imposed on presidents after a bloody uprising ousted the country's second leader in 2010.

Two of Mr Japarov's vote challengers, Mr Abdil Segizbayev and Mr Kursan Asanov, were detained by law enforcement earlier this week, raising fears that Mr Japarov's reign will continue the cycle of revenge that has defined local politics.

Mr Segizbayev, who was serving as national security chief at the time of Mr Japarov's arrest in 2017, was detained over charges of abuse of office.

Mr Asanov, who proclaimed himself acting interior minister during the same unrest that propelled Mr Japarov to power, has been detained for his alleged role in seizing the ministry building.

Mr Sooronbai Jeenbekov, who became the third Kyrgyz president to step down over unrest last year, was shown attending Mr Japarov's inauguration.

Thousands rose up after a parliamentary vote saw parties close to Mr Jeenbekov dominate, amid allegations of massive vote-buying.

The vote's results were subsequently annulled.

Russian leader Vladimir Putin last year called the overthrow of the previous government a "misfortune" and chided the country for seeking a political model based on Western democracies.