A Ukrainian court has sentenced former president Viktor Yanukovich to 13 years in prison for treason - attempting to quash a 2014 popular uprising.

Yanukovich was charged with high treason for asking Russian President Vladimir Putin to send Russian troops to Ukraine after he fled the ex-Soviet country.

"Yanukovich committed a crime against the foundation of Ukraine's national security," Judge Vladyslav Devyatko said in Kiev's Obolon district court on Thursday.

The 68-year-old had faced up to 15 years in prison but never attended the trial and is believed to be living in Russia after fleeing in 2014.

The uprising overthrew Yanukovich and brought to power President Petro Poroshenko, who faces an uphill battle for re-election in March.

The authorities beefed up security around the court as judges took turns to read out their ruling.

The court in Kiev has been holding hearings on the case since 2017.

Yanukovich faces a number of other criminal probes, including usurpation of power and using force against demonstrators.

In late 2013, the Moscow-backed president sparked massive protests when he refused, at the last minute, to sign an association accord forging closer ties between Ukraine and the European Union.

After Yanukovich fled, Putin revealed a special operation organised by Moscow had helped the Ukrainian leader escape.

Moscow annexed Ukraine's Crimea peninsula in 2014 and supported an uprising by Russian-speaking separatists in the east of the ex-Soviet country.

The conflict in eastern Ukraine has claimed more than 10,000 lives despite repeated international efforts to forge a lasting ceasefire.