Five people were killed and three injured following a rocket explosion on an Arctic naval test range in Russia, state nuclear company Rosatom confirmed.
The accident on Thursday happened during the testing of a liquid propellant rocket engine at a missile test site in the northwestern region
The three injured staff members suffered serious burns in the accident.
The company told Russian media that its engineering and technical team had been working on the “isotope power source” for the propulsion system.
Although the defence ministry said that no harmful chemicals were released into the atmosphere and that radiation levels were unchanged, authorities in the nearby city of Severodvinsk, about 30km from the test site, reported radiation levels shortly after the blast were higher than normal for about 40 minutes but returned to normal.
Two US-based experts suspected that the explosion and the radiation release resulted from a mishap during the testing of a nuclear-powered cruise missile at a facility outside the village of Nyonoksa.