A notorious pro-Russian militia commander in Donbass was assassinated by an explosives device placed in an elevator, according to reports.

Russian citizen Arsen Pavlov, nicknamed 'Motorola', was the commander of the 'Sparta' separatist militia battalion, which has fought Ukrainian government forces for control of Donbass Airport.

His unit is alleged to have tortured prisoners, and in one interview he boasted of having executed 15 Ukrainian POWs. Donbass is the stronghold of pro-Russian rebel groups who have engaged in a two-year conflict with Ukrainian forces, in which more than 9,000 people have been killed.

Pavlov was killed when an improvised explosive device exploded as he was entering the elevator of his Donestsk apartment building on 16 October, Interfax news agency reported. A bodyguard was also killed in the blast.

It came after Pavlov was injured by a bomb in a failed assassination attempt as he was leaving a hospital in June. The Donetsk separatist government said the explosive device was remotely detonated, and blamed Ukrainian special forces for the attack.

Several separatist leaders have been assassinated in the past year.

In a 2015 interview with the Georgian Journal, Pavlov, 33, claims he acquired his nickname as a wireman for the Russian military during "anti-terrorist operations in Chechnya".

According to reports he previously worked in a car wash in Rostov, and chose to enlist with a militia in Donbass in 2014 instead of being sent to prison after being caught joyriding by police.

A cartoonist who drew a satirical picture of Pavlov and his bride in 2014 said he was subsequently kidnapped and tortured by separatist militants.

The Ukrainian government in Kiev has not commented on the killing.