Russia pummelled Ukraine on Monday with one of the broadest barrages of missile attacks in weeks, claiming that it hit hundreds of targets in preparation for an anticipated eastern offensive. The attacks included a strike on the western city of Lviv, where seven people were killed in the first fatalities that city has suffered in the war.

The Russian defence ministry said it struck more than 300 military targets overnight, including fuel depots, warehouses and other infrastructure mainly in eastern Ukraine. Its forces were also closing in on the capture of the southeastern port city of Mariupol, where outnumbered Ukrainian fighters were defying demands to lay down their weapons at a sprawling steel plant that is the last obstacle to Russia’s completion of a “land bridge” to occupied Crimea.

There were growing signs that the new phase in Moscow’s onslaught against Ukraine — a push to seize more of the eastern region known as Donbas — was getting underway after weeks of military setbacks, including Russia’s retreat from areas surrounding Kyiv and the sinking of a major warship in the Black Sea.

Having failed in the early weeks of the war to destroy the Ukrainian military’s network of fuel and ammunition depots — perhaps under the mistaken assumption that Ukrainian forces would quickly surrender en masse — Russia has intensified its attacks against those facilities, as well as transportation infrastructure.

Three missile strikes in Lviv hit empty military warehouses and a fourth hit a garage overlooking a railway line, Ukrainian officials said.

At the same time, Russian forces have unleashed further destruction on major cities including Mykolaiv and Kharkiv, where six people were killed in attacks in residential areas on Sunday and Monday, local officials said.

Those attacks have tied up Ukrainian forces and prevented them from joining the fight farther east, while sowing terror among civilians after Russia failed to conquer these cities earlier in the war.

Ukrainian authorities said a Russian missile attack killed seven people in Lviv on Monday, the first civilian victims in the western city.

Lviv governor Maksym Kozytskyy said preliminary reports suggested four hits on Lviv, which is just 60km from the Polish border — three strikes on warehouses that are not currently being used by the military, and another on a car service station.

“It was a barbaric strike at a service station, it’s a completely civilian facility,” he told a news conference.

Andriy Sadoviy, mayor of Lviv, said the youngest victim among the seven killed was aged 30. The blast also wounded 11 and shattered windows of a hotel housing Ukrainians evacuated from elsewhere in the country, he added.

“Seven peaceful people had plans for life, but today their life stopped,” the mayor said.