A high-ranking general in the Russian armed forces and his assistant have been killed in an explosion in Moscow.

Lt Gen Igor Kirillov, head of the Nuclear, Biological, Chemical Defence Forces (NBC), was leaving a residential block early on Tuesday when a device hidden in a scooter was detonated, Russia's Investigative Committee said.

Pictures from the scene showed the entrance to a building badly damaged, with scorch marks on the walls and a number of windows blown out. Two body bags could also be seen on the street.

In October, the UK placed sanctions on Kirillov, saying he had overseen the use of chemical weapons in Ukraine and acted as a "significant mouthpiece for Kremlin disinformation".

On Monday, Ukraine's secret service, the SBU, charged him in absentia, saying on Telegram he was "responsible for the mass use of banned chemical weapons".

Russia denies the allegations.

The Investigative Committee, Russia's main investigative authority, said it had "opened a criminal case into the murder of two servicemen".

"Investigators, forensic experts and operational services are working at the scene," it said.

"Investigative actions and operational search activities are being carried out aimed at establishing all the circumstances of the crime."

Under UK sanctions, Kirillov was subject to an assets freeze and travel ban, with the Foreign Office describing him as a "significant mouthpiece for Kremlin disinformation".

In May, the US accused Russia of deploying chemical weapons as a "method of warfare" in Ukraine, in violation of international laws banning their use.

State Department officials said Russia used the choking agent chloropicrin to win "battlefield gains" over Ukraine.

The Kremlin rejected the accusations at the time, calling them "baseless".