An oil storage depot has been set on fire in a Russian city just north of Ukraine after what Russia described as an attack by two Ukrainian helicopters.
A video shared on Twitter showed a blaze near apartment blocks in Belgorod, 40 kilometres from the border.
Ukrainian aircraft have not struck targets in Russia previously. Kyiv will neither confirm nor deny the attack.
President Vladimir Putin’s spokesman said the incident cannot be perceived as creating comfortable conditions for continuing the talks with Kyiv.
So far the peace talks have made little progress.