The international post office in Moscow was evacuated Tuesday after radiation leveled 1 1/2 times higher than normal was detected coming from a package.
The package was emitting radiation, said Natalia Goncharova, a spokeswoman for the Emergency Situations Ministry.
A spokeswoman for a government agency called Radon said the package contained 30 compasses painted with a phosphorescent material she identified as radon-226.
The spokeswoman said the compasses were emitting radiation at a rate of about 300 microRoentgens an hour.
It was unclear where the packages had originated, the AP reports.
Roskosmos specialists started developing a medium-class reusable rocket in response to Falcon 9 carrier created by Elon Musk.