There has been a blast on a section of railway in Russia's Ural region, news agencies have reported.
A "bang" was heard near the city of Nizhny Tagil, TASS and RBC said.
In Russian media, "bang" is often used as a euphemism for a blast.
Baza - a Russian media outlet with security sources - said it happened close to an oil depot, near San-Donato station.
Last month, a Ukrainian source told Reuters that Ukraine's domestic spy agency had detonated explosives on a Russian railway line deep in Siberia.
That was apparently the second attack in a week on military supply routes in the area.
In the latest incident, Russian news agencies said there was no damage and no one was injured.
RBC, citing Russian Railways, said traffic in the area was "restricted" and some trains may be behind schedule.
