Kazakhstan has sentenced former prime minister Serik Akhmetov to 10 years in prison, a court said Saturday, the first time a former official of such stature will serve jail time in the country.

On Friday, a court in the industrial city of Karaganda found Akhmetov guilty on four corruption-related charges including embezzlement and abuse of power, in a huge case involving more than 20 defendants in the energy-rich state.

State television showed Akhmetov, 57, who filled the prime minister's role in 2012-14, begging for mercy from President Nursultan Nazarbayev while maintaining his innocence.

A total of 17 defendants including a former mayor of Karaganda were handed lesser criminal and administrative punishments, while three were acquitted, the court said in a statement.

Most of the defendants were state officials.

Graft remains endemic in the vast oil-producing country, which ranked 126th of 174 countries in Transparency International's Corruption Perceptions Index last year.

Nazarbayev, who has ruled the country with little opposition since before independence from the Soviet Union in 1991, regularly cites the need to battle corruption, but critics say the government has made few attempts to improve transparency.

Earlier this year corruption scandals engulfed preparations for EXPO 2017, a sustainable energy-themed exposition to be held in the capital Astana in mid-2017, which Kazakhstan expects to attract delegations from more than 100 countries.