MOSCOW (Reuters) -Russia said on Wednesday it had detained a citizen of Uzbekistan who had confessed to planting and detonating a bomb which killed Lieutenant General Igor Kirillov in Moscow a day earlier on the instructions of Ukraine’s security service.

Kirillov, who was chief of Russia’s Nuclear, Biological and Chemical Protection Troops, was killed outside his apartment building along with his assistant when a bomb hidden in an electric scooter went off.

He was the most senior Russian military officer to be assassinated inside Russia by Ukraine. Ukraine’s SBU intelligence service, which accused Kirillov of being responsible for the use of chemical weapons against Ukrainian troops, something Moscow denies, took responsibility for the killing.

Russia’s Investigative Committee, which probes serious crimes, said in a statement on Wednesday that the unnamed suspect had told them he had come to Moscow to carry out an assignment for Ukraine’s intelligence services.

In a video of the confession published by the Baza news outlet, which is known to have sources in Russian law enforcement circles, the suspect is seen sitting in a van describing his actions.

It was not clear what conditions he was speaking in and Reuters could not immediately verify the video’s authenticity.

Dressed in a winter coat, the suspect is shown saying he had come to Moscow at the orders of Ukraine’s intelligence services, bought an electric scooter, and then received an improvised explosive device to carry out the hit months later.

He describes how he had placed the device on the electric scooter which he had parked outside the entrance of the apartment block where Kirillov lived.

Investigators cited him as saying that he had set up a surveillance camera in a hire car nearby and that the organisers of the assassination, who he was cited as saying had been based in the Ukrainian city of Dnipro, had used the camera to watch what was going on.

In the video, the suspect, who was born in 1995, is shown saying that he had remotely detonated the device once Kirillov had left the building.

He says Ukraine had offered him $100,000 for his role in the murder and residency in a European country.

Investigators said they were identifying other people involved in the hit and the daily Kommersant newspaper reported that one other suspect had been detained. Reuters could not independently confirm that.