Ukrainian air defenses downed 50 of 72 drones launched by Russia overnight and attacked one of Russia's largest oil refineries, Ukraine's military said on Sunday.

Military and civilian authorities did not immediately report casualties or damages.

Ukrainian President Volodymyr Zelenskiy said Russia had used 1,250 aerial bombs, over 750 attack drones and more than 20 missiles to attack Ukraine over the past week.

"Only determination can stop such terrorists. We are constantly working with our partners to strengthen our defense capabilities and to reduce Russia's ability to terrorize Ukraine," Zelenskiy said on Telegram messenger.

"Long-range capabilities are crucial. Sanctions are essential. Lowering the price of oil is important. The key is to act in unity and protect lives with resolve," he added.

Kyiv's general staff said on Sunday its forces attacked Russia's Ryazan oil refinery again last night and explosions and fire were reported in the target area.

"The Ryazan Oil Refinery is one of the four largest refineries in the Russian Federation," it said on Telegram.

Russia's Defence Ministry said on Sunday that its air defense systems destroyed 15 Ukrainian drones over Russia and two sea drones in the Black Sea.

It said eight drones were downed over the Ryazan region, six drones were destroyed in the Kursk region and one drone was hit over the Belgorod region overnight.

Ryazan governor Pavel Malkov said on Sunday there were no casualties in the latest drone attacks but authorities were still estimating the damage.