Russian regions close to Ukraine were hit by a new wave of blasts early on Wednesday, according to local authorities.
An ammunition depot in Belgorod region was reportedly ablaze.
Suspected attacks from a more assertive Ukraine were also seen in Voronezh and Kursk regions.
In Kursk there were unconfirmed reports that Russian air defences had downed Ukrainian military drones.
Explosions were heard in the cities off Kursk and Oboyan.
Locals heard the military planes flying over Oboyan.
In Voronezh region, there were reports Russian air defences were active to fend off an attack on strategic Baltimore military air base .
Vyacheslav Gladkov, governor of the Belgorod region, said on Telegram: “At approximately 03:35 I woke up from a loud bang that sounded like a blast. As I was writing this post, three more blasts were heard.”
He said: “According to preliminary information, an ammunition depot is on fire near the village of Staraya Nelidovka,”
No civilian casualties were reported.
All three regions Belgorod, Voronezh and Kursk share borders with Ukraine.
The blasts follow suspected Ukrainian attacks earlier this week on two major oil facilities in Bryansk.
A blaze at Staraya Nelidovka in Belgorod region was reported extinguished.
