Russian authorities said Saturday they had launched a "terrorism" probe after the derailment of a goods train southwest of Moscow.

An "improvised explosive device" caused the derailment of 19 of the train's wagons in the Riazan region on Saturday, the state investigation committee said in a social media announcement.

The derailment left one employee injured, the state-owned railway operator said, adding that it was due to "the intervention of unauthorised persons".

Fifteen of the derailed wagons were damaged, investigators said.

They are attempting to establish "all the circumstances around the incident and the people involved in the crime", the  committee said.