An explosion has derailed a freight train for the second day in a row in a Russian region bordering Ukraine, 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 carried out 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 firefighters were working at the scene and two recovery trains had been dispatched to the area.
Local prosecutors have begun an investigation into the derailment, it added.
Operator Russian Railways earlier said around 20 wagons had come off the track due to "unauthorised interference".
Snezhetskaya is just to the southeast of Bryansk.
A freight train derailed around 150km to the west of Bryansk yesterday 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.
Meanwhile, Ukraine's military has vowed not to give up the eastern city of Bakhmut as it prepares to launch a counteroffensive against Russian forces.
General Oleksandr Syrskyi, commander of Ukrainian ground forces, underlined the importance Kyiv attaches to holding Bakhmut as preparations continue for a counterattack which it hopes will change the dynamic of the war in Ukraine.
The battle for Bakhmut has symbolic importance for both sides, with Ukraine still holding on to some parts of the city after months of fierce fighting against regular Russian troops and fighters from the Wagner mercenary force.
"Together with the commanders, we have made a number of necessary decisions aimed at ensuring the effective defence and inflicting maximum losses on the enemy," General Syrskyi said in remarks released after a visit to troops fighting in Bakhmut.
"We will continue, despite all the forecasts and advice, to hold Bakhmut, destroying Wagner and other most combat-capable units of the Russian army," he told soldiers in video footage of his visit.
"We give our reserves an opportunity to prepare and we are preparing for further actions ourselves."
General Syrskyi said Ukrainian units had ousted Russian forces from some positions in Bakhmut.
Ukraine's deputy defence minister Hanna Malyar said control of some parts of the city was changing hands.
"There are positions lost, and positions we are driving the enemy out of. Fierce fighting continues - as of now, the city is controlled by our armed forces," she told the WeUkraine television channel.
Wagner units advanced up to 160 metres in some directions today, founder Yevgeny Prigozhin said on the Telegram messaging app, repeating claims that Ukrainian forces now control less than 3sq/km of Bakhmut.
He also repeated his complaints that Moscow was not supplying his forces with enough ammunition.
Russia sees Bakhmut, once home to 70,000 people, as a stepping stone to attacking other Ukrainian cities.
Kyiv is widely expected soon to launch its counteroffensive, hoping to retake territory occupied by Russian forces after the invasion in February 2022.
The White House believes that more than 20,000 Russian fighters have been killed in Ukraine since December.
It said that Russia has exhausted its military stockpiles and its armed forces with some 100,000 Russian troops killed or wounded in Ukraine in the past five months.
Russian forces have steadily made incremental gains in Bakhmut, but Ukraine said on Sunday that it was still possible to supply the defenders with food, ammunition and medicine.
