Ramil Shamsutdinov pleaded guilty last year to carrying out the fatal gun attack in 2019 but complained of bullying in the army and a harassment culture he described as "hell".

The court in the Siberian city of Chita ruled Thursday that Shamsutdinov should serve his sentence of 24 years and six months in a "high security penal colony".

A jury in December last year found the soldier guilty but concluded that he deserved leniency, while prosecutors demanded he spend 25 years behind bar.

The Investigative Committee, which probes serious crimes, had earlier concluded that Shamsutdinov was of sound mind and health and understood the gravity of his actions.

In an open letter written after his arrest in 2019, Shamsutdinov said that "he had no other choice" and asked for forgiveness from the family and friends of his victims.

"I didn't expect that I would end up in such a hell. There was nowhere to run or to complain," he wrote in the letter that was shared on social media.

After the shooting, one of the soldiers that served in Shamsutdinov's unit was handed a two-year suspended sentence for bullying.

In a similar attack in November 2020, a 20-year-old soldier killed three fellow servicemen at a military base near the city of Voronezh where activists said conscripts were subjected to humiliating hazing rituals.

Military service is compulsory in Russia for men aged between 18 and 27, but many people use loopholes to evade conscription.

While authorities insist that bullying rituals that plagued the military in the 1990s have been rooted out in the Russian army, rights NGOs maintain that hazing remains a persistent problem.