The Russian prosecutor’s office said the suspect, a 29-year-old citizen of Uzbekistan, confessed to planting the bomb on the orders of Ukrainian agents.

The FSB said the suspected organisers of the attacks were planning to kill a senior defence official using a remotely controlled car bomb.

Russia’s security service says it has detained a citizen from Uzbekistan in the bombing that killed a senior general as he left his Moscow apartment — a bold assassination that was claimed by Ukraine’s security service.

The bombs were disguised as an electric scooter, a document folder and a magnetized portable charger, Russia's Federal Security Service said.