At least seven people were killed and dozens injured after a bridge collapsed onto a railway in a Russian region bordering Ukraine late Saturday, officials said, in an incident the railway operator blamed on "illegal interference".

A train travelling from the Russian border town of Klimovo to the capital Moscow was derailed in the incident, authorities said, without giving details.

Videos posted on social media showed rescuers working at the site of a large mound of rubble covering what appeared to be a train belonging to national operator Russian Railways, while another showed people shouting in distress.

"There are seven dead as a result of the collapse of a bridge onto railway tracks," Alexander Bogomaz, the Bryansk region's governor, wrote on Telegram.

At least 66 others were injured, including three children, he said, giving a revised toll.

Moscow Railways, a state-owned subsidiary, said a passenger train derailed "between Klimov and Moscow due to the collapse of a road bridge span, as a result of illegal interference in the operation of transport".

The incident happened at 10:44 PM between the Pilshino and Vygonichi stations in the Bryansk region, the national railway operator said on Telegram.

The incident did not affect other train traffic, the firm added.

In one video posted on social media, someone can be heard screaming as eyewitnesses rush to find help.

"How did the bridge collapse? There are children there!" a woman can be heard shouting in the video.

'Illegal interference'

Photos published online by Russian authorities showed a collapsed section of the bridge and damaged vehicles, as rescue workers were deployed overnight.

The disaster area is around 100 kilometers from the Ukrainian border.

Russia's emergency ministry said a team was on site, while Russian Railways said it had dispatched repair trains to the scene.

An AFP reporter in central Moscow saw ambulances parked at Kievsky railway station awaiting the arrival of injured passengers.

Prosecutors said they had opened an investigation.

Authorities did not explain how the incident happened and what the railway operator meant by "illegal interference".

Ukraine, which Russia has blamed for previous incidents, did not immediately comment.

Russia has been hit by dozens of sabotage attacks since Moscow launched its offensive against Ukraine in 2022, many targeting its vast railroad network.

Kyiv says Russia uses railroads to transport troops and weaponry to its forces fighting in Ukraine.

The incident came just two days before a possible meeting between Russian and Ukrainian officials in Istanbul, amid a US-led diplomatic push to end the three-year conflict.