It said the front locomotive and seven wagons derailed “after the intervention of unauthorized persons.”
“As a result of the incident, the locomotive caught fire,” it said in a statement.
It later said that the fire had been put out by 12.30 pm local time and that passengers of two Moscow-bound trains in the area would be taken by bus to the regional capital Bryansk.
Footage on social media showed the front of the train and several cargo carriages on fire and lying on the grass next to the tracks.
There have been reports of sabotage acts on railroads in Russia and its ally Belarus throughout Moscow’s more than year-long Ukraine offensive.
Also on Monday, the governor of the northern Leningrad region, Alexander Drozdenko, said local power lines had been blown up by an “explosive device.”
The official said the lines were damaged near the village of Susanino, 60 kilometers south of Russia’s second city St. Petersburg and posted images of the lines lying on the ground in a forest.
Drozdenko later said the FSB security service had opened a criminal case on “sabotage.”