An explosion killed an army officer in a closed-off military town in Russia’s far east this week, in what appeared to be an attempt to target a more senior commander known as the “Butcher of Bucha”.

Three sources familiar with the incident said the bomb detonated at about 9am on Tuesday in a residential block in Knyaze-Volkonskoye-1, the home of Maj Gen Azatbek Omurbekov, who commanded Russian troops during the occupation of Bucha.

Two sources said the assailant had placed the bomb in a mailbox between the first and second floors and installed a camera. The attacker targeted the wrong entrance, however: a subordinate was killed in the blast, but Omurbekov was not injured, the sources said.

The EU has placed sanctions on Omurbekov over his role in the massacre of civilians in the Ukrainian town of Bucha, where Russian troops are accused of killing more than 400 civilians.

Neither Russia nor Ukraine has commented on the incident. Ukrainian intelligence agencies have targeted dozens of senior Russian military officers and Russian-installed officials since the start of the war, accusing them of involvement in war crimes.

VChK-OGPU, an anonymous Telegram channel with reported links to Russia’s security services, stated on Tuesday evening that the blast had been intended to target Omurbekov, adding that it killed a lieutenant colonel identified only by his surname, Kuzmenko.

Omurbekov’s apartment block, which was primarily used by military officials, had been cordoned off, sources said, and the garrison was being patrolled by troops.

Knyaze-Volkonskoye-1 is a small military settlement on the outskirts of Khabarovsk, in Russia’s remote far east, close to the Chinese border. Unlike a typical civilian town, it is a garrison community built around a nearby army base: access is controlled at checkpoints and non-residents require permission to enter.

Little is known about the clandestine Ukrainian cells behind assassinations and attacks on military infrastructure inside Russia and in Russian-controlled territories.

Ukraine is believed to be responsible for the attempted assassination in February of Lt Gen Vladimir Alekseyev, a senior Russian military official who has a central role in the country’s intelligence services. Alekseyev was shot several times in the stairwell of his apartment block by an unknown gunman but survived the attack.

Omurbekov’s profile would make him a high-value target for Ukraine’s intelligence services.

He commanded the 64th Separate Guards Motor Rifle Brigade, an elite infantry unit, during the occupation of Bucha in 2022 – and is believed to be one of the bloodiest commanders to have served there. The British sanctions list accuses him of being in “direct command” of troops involved in the killing of civilians.

In an interview with the Russian outlet iStories, one of Omurbekov’s subordinates in Bucha said the commander routinely ordered the killing of civilians, including attacks on vehicles carrying non-combatants.

Despite overwhelming evidence, Russian officials have denied their troops killed civilians in Bucha, and at a secret ceremony Vladimir Putin awarded Omurbekov the title of hero of the Russian Federation, the country’s highest honour. He was later transferred to the 392nd District Training Centre in Knyaze-Volkonskoye-1.

While the bombing appeared not to have reached its intended target, the fact it took place in a far-flung military town represented the latest security failure by Russia’s FSB, said Andrei Soldatov, an expert on Russian intelligence services.

“Given the massive resources military counterintelligence has at its disposal to protect personnel, this is a security lapse,” he said.

“The protection of military personnel has long been a priority for the FSB. Officers are assigned within military districts specifically to oversee their security.”