Ukraine has launched its second major drone attack in a week against Russian oil refineries hundreds of miles from its borders.

"This refinery is one of the 10 largest oil refineries in Russia in terms of design capacity and is involved in supplying the Russian occupatying army," the General Staff said in a statement.

Officials say a Russian drone has blasted a hole in an apartment building in northeastern Ukraine during a nighttime attack that killed at least six people and wounded nine others.

A new drone bomber may have joined Ukraine’s escalating assault on Russia’s oil industry. On Wednesday night or early Thursday morning, drones operated by the Ukrainian 14th Separate Unmanned Aerial Vehicle Regiment struck a pumping station on the Druzhba pipeline along the Russian-Belarusian border in Bryansk Oblast.

A Russian drone struck a multi-storey apartment building in the northeastern Ukrainian city of Sumy early on Thursday, killing nine people and injuring 13, including a child, President Volodymyr Zelenskiy said.

A Russian drone attack on a residential block killed eight people including three elderly couples in the eastern Ukrainian city of Sumy, prosecutors said on Thursday.

Ukrainian soldiers are now using a long-range drone capable of traveling up to 2,000 kilometers (1,242 miles) and carrying a 250-kilogram air bomb, the Unmanned Systems Forces said on Jan. 31. The drone is described as a “unique development” and a potential game changer on the battlefield.