Russian President Vladimir Putin has said the August 8 accident at a northern military base occurred during the test of a weapons system, but he added that he could not reveal everything about the incident for security reasons.
Speaking on August 21 during a visit to Finland to meet his counterpart, Sauli Niinisto, Putin said all services monitoring radiation were working and that radiation levels were normal, adding that the same applied for neighboring countries.
He added in his wide-ranging remarks that it was important for Europe to start sharing information on such accidents in the future.
The accident in the northern Russian region of Arkhangelsk, which killed at least five people and injured several others, raised concerns of atmospheric contamination after emergency officials reported a spike in background radiation levels.
The White Sea bay where both the shipbuilding port and the regional capital, Arkhangelsk, are located were ordered closed for swimming and fishing, due to the presence of toxic rocket fuel.
Following the accident, there were reports of panic buying of iodine drops in the nearby shipbuilding town of Severodvinsk. Iodine is often taken to protect the thyroid gland from some types of radiation.
Putin on August 19 said there was "no threat" of contamination after the deadly blast, which occurred in the town of Nyonoksa, a Dvina Bay port not far from Severodvinsk, at a naval site that has been used for decades to test naval missiles, including intercontinental ballistic missiles.
Some U.S. officials have said they believe radioactive elements were involved, and many analysts have focused attention on a nuclear-powered cruise missile that Putin announced was under development last year.