Russian reports say Ukrainian drones have struck a Russian arms depot deep inside the country, triggering explosions and the closure of a major highway.

A Ukrainian drone attack launched overnight succeeded in destroying an ammunition depot in the western Russian region of Tver, a source from Ukraine’s Security Service (SBU) told CNN on Wednesday.

Russia said it was working to repel a Ukrainian drone attack on Toropets, where there's a major military depot, as explosions lit up the night.