Russia's top security agency says it has arrested four Russians accused of making preparations to kill senior Defense Ministry officials on Ukraine's orders.

Russian security officials said it arrested four Russians accused of planning to kill senior officials with the Defense Ministry.

According to the Federal Security Service (FSB), four Russians were involved 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 head of Russia's chemical and biological forces, Lt. General Igor Kirillov, was killed in a Moscow bomb blast claimed by Ukraine.

Kirillov ran Russia’s nuclear, biological and chemical defense forces. Kyiv previously accused him of ordering the use of chemical weapons against Ukraine.

Kirillov, who has been killed in Moscow, was accused by the West of overseeing the use of chemical weapons on the battlefield in Ukraine.

It is believed that the bomb was hidden in or on an electric scooter at the location, which emergency teams were seen examining.

Russia said on Wednesday it had detained an Uzbek man who had confessed to planting and detonating a bomb which killed a top general, Igor Kirillov, in Moscow on the instructions of Ukraine’s SBU security service.

Lieutenant General Igor Kirillov was the head of Russia's Nuclear, Biological, and Chemical Protection Troops. Authorities said the explosion was caused by a bomb hidden inside an electric scooter.

Lieutenant General Igor Kirillov, head of Russia’s Nuclear, Biological, Chemical Defence Forces (NBC), was killed in an explosion in Moscow in an assassination claimed by Ukraine

Russia’s top security agency says it has arrested four Russians accused of making preparations to kill senior Defense Ministry officials on Ukraine's orders.