By Maria Starkova and Pavel Polityuk
LVIV/KYIV (Reuters) - Ukraine said on Monday Russia had started an anticipated new offensive in the east of the country while a Russian missile attack killed seven people in Lviv, the first civilian victims in the western city about 60 km (40 miles) from Poland.
Ukrainian officials said Russian shelling killed another four people in the eastern Donetsk region on Monday, while a man and a woman were killed in Kharkiv, in the northeast, when shells hit a playground near a residential building.
Ukrainian President Volodymyr Zelenskiy said Russian forces had begun the "Battle of Donbas" after senior officials said Moscow had begun a new offensive push along most of Ukraine's eastern flank.
"A very large part of the entire Russian army is now focused on this offensive," Zelenskiy said in a video address, adding: "No matter how many Russian troops they send there, we will fight. We will defend ourselves."
Ukrainian media reported a series of explosions, some powerful, along the front line in the Donetsk region, with shelling taking place in Marinka, Slavyansk and Kramatorsk. Ukrainian officials and local media also said further explosions were heard in Kharkiv, Mykolaiv in the south and Zaporizhzhia in the southeast.
Reuters was not immediately able to verify the reports.
Earlier, Ukraine's top security official, Oleksiy Danilov, said Russian forces attempted to break through Ukrainian defences on Monday "along almost the entire front line of Donetsk, Luhansk and Kharkiv regions."
Zelenskiy's chief of staff Andriy Yermak called it "the second phase of the war" and assured Ukrainians their forces could hold off the offensive. "Believe in our army, it is very strong," he said.
Maksym Kozytskyy, the governor of Lviv, said preliminary reports suggested there were four strikes there, three on warehouses 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.
The mayor of Lviv, Andriy Sadoviy, said the blast also wounded 11 and shattered windows of a hotel housing evacuees from elsewhere in the country.
"Seven peaceful people had plans for life, but today their life stopped," he said.
Driven back by Ukrainian resistance in the north, Moscow has refocused its ground offensive in the two eastern provinces known as the Donbas, while launching long-distance strikes at other targets including the capital, Kyiv.
The regional governor of Kharkiv said authorities were continuing to evacuate people from two areas where they expect fighting to take place.
Russia's defence ministry said it had hit hundreds of military targets in Ukraine overnight. It said air-launched missiles had destroyed 16 military facilities across Ukraine.
It added that the Russian air force had launched strikes against 108 areas where Ukrainian forces were concentrated and Russian artillery struck 315 Ukrainian military targets.
Western capitals and Kyiv accuse Russian President Vladimir Putin of unprovoked aggression.
Russia denies targeting civilians in what it calls a special operation to demilitarise Ukraine and eradicate dangerous nationalists. It rejects what Ukraine says is evidence of atrocities, saying Ukraine has staged them to undermine peace talks.
Last week, U.S. President Joe Biden announced an additional $800 million in military assistance to Ukraine, expanding the aid to include heavy artillery ahead of a wider Russian assault expected in eastern Ukraine.
The U.S. military expects to start training Ukrainians on using howitzer artillery in coming days, a senior U.S. defence official said on Monday, adding the training would take place outside Ukraine.
French President Emmanuel Macron said on Monday his dialogue with Putin had stalled after mass killings were discovered in Ukraine.
'HELL ON EARTH'
Russia has been trying to take full control of the southeastern port city of Mariupol, which has been besieged for weeks and which would be a huge strategic prize, linking territory held by pro-Russian separatists in the east with the Crimea region that Moscow annexed in 2014.
Major Serhiy Volyna, commander of Ukraine's 36th marine brigade which is still fighting in Mariupol, appealed for help in a letter to Pope Francis, saying women and children were trapped among fighters in the city's steel works.
"This is what hell looks like on earth ... It's time (for) help not just by prayers. Save our lives from satanic hands," the letter said, according to excerpts tweeted by Ukraine's ambassador to the Vatican.
No fewer than 1,000 civilians were hiding in underground shelters beneath the vast Azovstal steel plant, the city council said on Monday.
Video and audio footage showed explosions rumbling and smoke rising from the steelworks, which contain myriad buildings, blast furnaces and rail tracks.
Azovstal is the main remaining stronghold of Ukrainian forces in Mariupol. The city's defenders include Ukrainian marines, motorised brigades, a National Guard brigade and the Azov Regiment, a militia created by far-right nationalists that was later incorporated into the National Guard.
Denis Prokopenko, a lieutenant colonel of the Azov Regiment, said in a Telegram video post that while he was at the steel plant, Russian and separatist forces were dropping anti-bunker bombs and blasting the area with rockets and other weapons, including from ships, "knowing that there are civilians here."
Russia's invasion has damaged or destroyed up to 30% of Ukraine's infrastructure at a cost of $100 billion, a Ukrainian minister said, adding reconstruction could be achieved in two years using frozen Russian assets to help finance it.
The United Nations said on Monday the civilian death toll from the war had surpassed 2,000, reaching 2,072 as of midnight on April 17 from the start of the Russian invasion on Feb. 24.
About 4 million Ukrainians have fled the country.
(Reporting by Reuters journalists in Kyiv and Lviv; Additional reporting by Lidia Kelly in Melbourne and Ronald Popeski in Winnipeg and Reuters bureaus worldwide; Writing by Alexandra Hudson, Keith Weir and David Brunnstrom; Editing by Edmund Blair, Nick Macfie, Cynthia Osterman and Lincoln Feast.)