Russia’s top security agency says that it has arrested several suspects accused of involvement in an alleged Ukrainian plot to assassinate senior military officers.

Russia has arrested four people on suspicion of plotting to assassinate senior defence officials and their families on Ukraine’s orders, the Kremlin’s Federal Security Service (FSB) said.

The arrest announcement follows the death of Russia's Lt. Gen Igor Kirillov, who was killed on Dec. 17 by a bomb hidden on an electric scooter parked outside his apartment building.

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

Russia's Federal Security Service (FSB) has detained four Russians who allegedly were preparing a series of terrorist attacks against high-ranking Defense Ministry officials and their families, the agency's press service said on Dec.