Explosions echoed over Kyiv on Tuesday during a rare daytime Russian drone attack on the capital, after the two sides launched strikes that left six dead.

A major oil refinery in southern Russia was also set ablaze, triggering a local state of emergency as thick black smoke billowed over the coastal town of Tuapse.

Russia has pummelled Ukrainian cities since invading the country more than four years ago, mainly by launching long-range aerial barrages at night.

AFP journalists in Kyiv heard air raid sirens ring out and at least one loud boom over the city shortly after 2:15pm (1115 GMT).

City officials announced that air defence systems were operating against Russian drones flying over the city and that two people were hurt in the attack.

Kyiv and Moscow have stepped up their aerial attacks over recent months, with both sides mainly targeting energy infrastructure.

A Ukrainian drone attack earlier killed three people in the Russian border region of Belgorod and one more in the neighbouring Bryansk region.

Ukrainian authorities meanwhile said two people were killed in the central Dnipropetrovsk region and in the eastern Kharkiv region.

Kyiv confirmed its forces had targeted oil facilities in Tuapse.

‘This production is involved in supplying Russia’s occupation army in Ukraine,’ it said.

Footage published online by the Krasnodar regional governor showed fire and thick smoke at the site of the Tuapse oil refinery.