Aug. 13 (UPI) -- Russian officials said Tuesday radiation levels at a military test site involved in an explosion last week were four to 16 times above natural background levels.
Five were killed during a military drill in the nation's northwest Arkhangelsk region where the Russian defense ministry said troops were testing a liquid propulsion system at a military range.
The explosion led to a spike in radiation in Severodinvsk, but later returned to normal, officials said. Rosgidromet, Russia's weather watching service, said that the spike was significant.
"As at 12:00 on Aug. 8, 2019 the Arkhangelsk territorial system of radiation control registered gamma radiation levels 4-16 times above the background rate of the ambient dose equivalent for the given territory," the service's report said.
Leonid Bolshov, of the Russian Academy of Sciences' Nuclear Safety Institute, told TASS the explosion offered no risk to the population of the Arkhangelsk region. Valentin Magomedov, of the city's civil defense department, said radiation in Severodvinsk was three times the permissible level, though.
Russia has given little information about what happened at the military site but said that five scientists died at the site after initially saying the accident caused two deaths.
The scientists were buried Monday after being awarded the Order of Courage posthumously. The award honors Russians performing military, civic or professional duties "with risk to one's life."
U.S. officials increasingly believe that the explosion was part of tests for a new cruise missile charged by nuclear power, which could have contaminated the region. Russian media speculated that it could be the SSC-X-9 Skyfall, a nuclear-powered cruise missile Russian President Vladimir Putin bragged about last year.