The commander of Russian armed forces' chemical, biological and radiation defence troops, Igor Kirillov, was killed along with his assistant when the blast went off as the two men left a building in southeastern Moscow early that morning.

"An explosive device planted in a scooter parked near the entrance of a residential building was activated on the morning of December 17 on Ryazansky Avenue in Moscow," said the Russian Investigative Committee, responsible for major investigations in the country.

The blast shattered several windows of the building and severely damaged the front door, according to images published by Russian media.

Kirillov, who had been in his post since 2017, was sanctioned in October by Britain over the alleged use of chemical weapons in Ukraine.

The blast comes as what Moscow calls its special military operation in Ukraine nears its third anniversary.