MOSCOW (Reuters) -A Ukrainian drone attack derailed a freight train and sparked a fire in a diesel tank in the southern Russian region of Volgograd, mangling several hundred metres of track, Russian media said on Tuesday.

Russian Railways said simply that the derailment was caused by interference by unauthorised persons, but Russian media said the train was attacked by a drone.

Footage published by Baza, a Telegram channel linked to Russia's security services, showed freight wagons strewn alongside a railway line.

"As a result of interference by unauthorised persons into the operation of railway transport, cars of a freight train derailed at the Kotluban station," Russian Railways said.

"According to preliminary information, there were no injuries. At this time, train traffic in the area of the Kotluban station is suspended."

The storage tank and cars with lumber caught fire and the blaze was extinguished, Russia's RIA state news agency reported, citing the emergency ministry.

TASS, another state news agency, cited emergency services as saying that 300 metres of track had been damaged in the incident.

There was no immediate word from Ukrainian officials about the incident. Kyiv has said in the past it has carried out sabotage attacks on Russia's railway system to disrupt military logistics, including far from the front lines in the nearly 27-month-old war.

Ukraine says that targeting Russia's military, transport and energy infrastructure undermines Moscow's war effort and is an answer to the countless deadly attacks on Ukrainian infrastructure by Russia.

(Reporting by Lidia Kelly in Melbourne and Guy Faulconbridge in Moscow; Editing by Himani Sarkar, Stephen Coates, Peter Graff)