Russian's state nuclear company says five people were killed in Thursday's rocket explosion on a naval test range.
A statement from Rosatom said three people were also injured in the incident.
They say the staff members suffered serious burns in the accident, which has been shrouded by mystery.
On Friday Russian government sources said two people died and six were injured in the Nyonoksa blast.

Zambia steps up Ebola screening as neighbouring Congo sees cases rise
Pentagon chief says US ready to restart strikes on Iran if no deal
Flights briefly halted at Munich Airport over possible drone sighting
Myanmar's junta chief turned president heads to India
