Multiple explosions apparently caused by missiles have struck the western Ukrainian city of Lviv as the country braced for an all-out Russian assault in the east. 

At least six people were killed as plumes of black smoke rose over the city after the blasts. 

Lviv and the rest of western Ukraine have been less affected by two months of fighting than other parts of the country and have been considered a relative haven.

Lviv’s regional governor Maksym Kozytsky said six people were killed and another eight, including a child, were wounded by four Russian missile strikes. 

He said three hit military infrastructure facilities and one struck a tyre shop, and that emergency teams were putting out fires.

Lviv Mayor Andriy Sadovyi put the toll at six dead and 11 wounded, including one child.

Military analysts say Russia is increasing its strikes on weapons factories, railways and other infrastructure targets across Ukraine to wear down the country’s ability to resist a major ground offensive in the Donbas, Ukraine’s Russian-speaking eastern industrial heartland.

The fall of Mariupol, which has been reduced to rubble in a seven-week siege, would give Moscow its biggest victory of the war. But a few thousand fighters, by Russia’s estimate, are holding on to the giant four-square-mile Azovstal steel mill.

“We will fight absolutely to the end, to the win, in this war,” Ukrainian Prime Minister Denys Shmyhal vowed on Sunday. 

He said Ukraine is prepared to end the war through diplomacy if possible “but we do not have intention to surrender”.

Many Mariupol civilians, including children, are also sheltering at the Azovstal plant, Mikhail Vershinin, head of the city’s patrol police, told Mariupol television. He said they are hiding from Russian shelling and from any occupying Russian soldiers.

Capturing the city on the Sea of Azov would free up Russian troops for the expected new offensive to take control of the Donbas, in Ukraine’s industrial east. 

HeraldScotland: Firefighters battle a blaze after a civilian building was hit by a Russian missile on April 18, 2022 in Lviv, Ukraine. (Photo by Joe Raedle/Getty Images)Firefighters battle a blaze after a civilian building was hit by a Russian missile on April 18, 2022 in Lviv, Ukraine. (Photo by Joe Raedle/Getty Images)

It also would allow Russia to fully secure a land corridor to the Crimean Peninsula, which it seized from Ukraine in 2014, and deprive Ukraine of a major port and its prized industrial assets.

Russia is bent on capturing the Donbas, where Moscow-backed separatists already control some territory, since its attempt to take the capital Kyiv failed.

“We are doing everything to ensure the defence” of eastern Ukraine, Ukrainian President Volodymyr Zelensky said in his nightly address to the nation.

As for besieged Mariupol, there appeared to be little hope of military rescue by Ukrainian forces any time soon. 

Foreign Minister Dmytro Kuleba said on Sunday that the remaining Ukrainian troops and civilians there are basically encircled. 

He said they “continue their struggle” but that the city effectively does not exist any more because of massive destruction.

The relentless bombardment and street fighting in Mariupol have killed at least 21,000 people, by Ukrainian estimates. 

A maternity hospital was hit by a lethal Russian air strike in the opening weeks of the war, and about 300 people were reported killed in the bombing of a theatre where civilians were taking shelter.

An estimated 100,000 people remained in the city out of a pre-war population of 450,000, trapped without food, water, heat or electricity.

Drone footage carried by the Russian news agency RIA-Novosti on Sunday showed mile after mile of shattered buildings and, on the city’s outskirts, the steel complex from which rose towering plumes of smoke.

Ukrainian Deputy Defence Minister Hanna Malyar described Mariupol as a “shield defending Ukraine”.

Russian forces, meanwhile, carried out aerial attacks near Kyiv and elsewhere in an apparent effort to weaken Ukraine’s military capacity ahead of the anticipated assault on the Donbas.

After the humiliating sinking of the flagship of Russia’s Black Sea Fleet last week in what the Ukrainians boasted was a missile attack, the Kremlin has vowed to step up strikes on the capital.

Russia said on Sunday that it had attacked an ammunition plant near Kyiv overnight with precision-guided missiles, the third such strike in as many days. 

Explosions were also reported in Kramatorsk, the eastern city where rockets earlier this month killed at least 57 people at a train station crowded with civilians trying to evacuate ahead of the Russian offensive.