An oil storage depot is on fire in a Russian city just north of Ukraine after what the local governor said was an attack by two Ukrainian helicopters.
A video shared on Twitter shows a blaze near apartment blocks in Belgorod, some 40km (25 miles) from the border.
Some clips appear to show rockets hitting the oil depot.
However, Ukraine has not previously struck targets in Russia and governor Vyacheslav Gladkov’s allegation was not confirmed by Ukrainian officials.
Belgorod, a city of 370,000, lies just north of Ukraine’s second city Kharkiv, which has been heavily shelled by Russian artillery and remains surrounded by Russian forces.
Governor Gladkov said in a Telegram message “there was a fire at the oil depot because of an air strike carried out by two Ukrainian army helicopters, which entered Russian territory at low altitude”. “Nobody was killed,” he added.
He said emergency workers were trying to contain the fire as quickly as possible and that there was “no threat” to residents. The emergencies ministry posted video of the blaze on Telegram.
Interfax news agency reported that residents nearby were evacuated and two people were injured at the depot. It said eight fuel tanks were on fire and nearly 200 firefighters were on the scene. The depot is run by Russian state oil firm Rosneft.
On 29 March several explosions were reported at an ammunition depot near Belgorod.