An explosion derailed a freight train for the second day in a row in a Russian region bordering Ukraine on Tuesday, sending both the locomotive and some cars off the tracks, authorities said.

The incident occurred in the western Bryansk region, which borders both Ukraine and Belarus. Russian officials say pro-Ukrainian sabotage groups have made multiple attacks there since Russia invaded Ukraine in February 2022.

“An unidentified explosive device went off near the Snezhetskaya railway station. There were no casualties," Bryansk regional governor Alexander Bogomaz wrote on Telegram.

“As a result of the incident, a locomotive and several wagons of a freight train derailed," he added, without saying who was responsible.

Tass news agency, citing law enforcement agencies, said fire fighters were working at the scene and two recovery trains had been dispatched to the area. Local prosecutors had begun an investigation into the derailment, it added.

Operator Russian Railways earlier said around 20 wagons had come off the tracks due to “unauthorised interference”. Snezhetskaya is just to the southeast of Bryansk.

A freight train derailed around 150 km (90 miles) to the west of Bryansk on Monday after a blast. Pictures of that incident shared on social media showed several tank carriages lying on their side and dark grey smoke billowing into the air. (Reuters via VOA)

•PHOTO:The incidents come as Kyiv says it is preparing for a counteroffensive and after Ukraine’s military promised to keep defending the eastern city of Bakhmut [File: Sofiia Gatilova/Reuters]