MOSCOW • Russia said yesterday that an explosion at an Arctic missile testing site killed five nuclear agency staff and involved radioactive isotopes after a nearby city reported a spike in radiation levels.
In a statement, Russia's nuclear agency, Rosatom, said the accident on Thursday at a secret military facility also left three staff with burns and other injuries.
The military had not previously described the accident as involving nuclear fuel and said radiation levels were normal afterwards.
But officials in the nearby city of Severodvinsk reported that radiation levels were briefly raised after the accident.
The accident occurred in the far northern Arkhangelsk region during testing of a liquid-propellant jet engine.
An explosion sparked a fire, killing two, the Defence Ministry said in a brief statement.
Rosatom said its staff were providing engineering and technical support for the "isotope power source" of the engine being tested.
The authorities have released few details of the accident at the Nyonoksa test site on the White Sea, used for testing missiles deployed in nuclear submarines and ships since the Soviet era.
The Defence Ministry said six of the ministry's employees and a developer were injured while two "specialists" died of their wounds.
It was not immediately clear whether the death toll reported by Rosatom included the fatalities announced earlier by the Defence Ministry.
Russian state news agencies quoted a Defence Ministry source as saying that both ministry and Rosatom employees were killed.
The authorities in Severodvinsk, 30km from the test site, said on their website on Thursday that automatic radiation detection sensors in the city "recorded a brief rise in radiation levels" around noon that day.
The post was later taken down and the Defence Ministry said that radiation levels were normal after the accident.
An official responsible for civil defence, Mr Valentin Magomedov, told Tass state news agency on Thursday that radiation levels rose to 2.0 microsieverts an hour for half an hour from 11.50am, before falling sharply.
He said this exceeded the permitted limit of 0.6 microsieverts, Tass reported.
Russian online media published unattributed video that journalists said showed a line of ambulances speeding through Moscow to take the injured to a centre that specialises in the treatment of radiation victims.
Rosatom said that the injured were being treated at a "specialised medical centre".
The news of the accident prompted residents of Severodvinsk to rush to pharmacies on Thursday to stock up on iodine, which can be taken to stop the thyroid gland absorbing radiation.