Russian strikes hit eastern Ukraine's city of Kharkiv late Tuesday, the regional governor said, just hours after a surprise visit by the German foreign minister with her Ukrainian counterpart.
Annalena Baerbock vowed further German support for Kyiv on her unannounced trip, but Ukraine's top diplomat Dmytro Kuleba said Berlin's refusal to send his country battle tanks was costing lives.
German Chancellor Olaf Scholz recently agreed to provide to Ukraine Marder infantry fighting vehicles long sought by Kyiv in its battle against Russia's invasion.
But Berlin has so far declined to supply Ukraine with more advanced Leopard battle tanks. Kuleba, accompanying Baerbock during her visit to the eastern city of Kharkiv, pressed Germany again to send them.
The "longer it takes to make the decision, the more people will die", he said.
"I have no doubt that Ukraine will receive German Leopard tanks. I think the German government somewhere deep down understands that this decision will be made and the tanks will be transferred to Ukraine."
Kharkiv has faced heavy bombardment during the war, but the frontline has moved east since a Ukrainian counter-offensive last year retook territory from Russian forces.
"Stay in the shelters. The occupiers are bombing again!" regional governor Oleg Synegubov warned on Telegram. An AFP journalist heard several explosions in the city.
Baerbock, who on Tuesday became the highest-level Western official to visit Kharkiv, had pledged further German support for Kyiv.
"In all parts of Ukraine, from Kharkiv to Kherson to Kyiv, people should know they can rely on our solidarity and support," she said.
She stressed that Germany will keep supplying weapons "that Ukraine needs in order to free its citizens who are still suffering under the terror of Russian occupation".
Baerbock brought with her a "further help package" of power generators, 20 million euros ($21 million) for demining and 20 million euros as financial help for the Starlink project ensuring internet access for the population.
- Putin ally stripped of citizenship -
Ukraine's President Volodymyr Zelensky on Tuesday said he had revoked the citizenship of Viktor Medvedchuk, once seen as Russian leader Vladimir Putin's top ally in Kyiv and accused of high treason.
Medvedchuk, a former Ukrainian lawmaker who was handed over to Russia in a prisoner exchange last September, was stripped of his citizenship along with three others, Zelensky said in his daily address.
Based on materials prepared by Ukraine's security and state migration services and in accordance with the constitution, "I have decided to terminate the citizenship of four persons," Zelensky said.
He said the actions were appropriate for those who "choose to serve not the people of Ukraine, but the murderers who came to Ukraine".
Ukrainian tycoon Medvedchuk was captured in April last year by Ukraine's special services, after fleeing home arrest when Russia invaded.
The super-rich powerbroker -- once dubbed the "dark prince" of Ukrainian politics -- was accused of high treason and attempting to steal natural resources from Russia-annexed Crimea and of handing Ukrainian military secrets to Moscow.
- 'Symbol of incredible perseverance' -
Several Western leaders including Scholz and French President Emmanuel Macron have visited Ukraine since Russia's invasion on February 24, 2022.
But none have travelled so far east as Baerbock, where swathes of territory are under Russian control.
Baerbock's visit was kept secret for security reasons and announced only as she made her way back to Berlin.
She said she wanted to get a picture of the situation on the ground and send her message of solidarity to Ukrainians.
Baerbock called the city a "symbol of the Ukrainians' incredible perseverance and courage", as she noted that deep traces of the destruction wrought by Russian forces were still visible "practically on every street corner".
Kharkiv was not just a city of the country's "successful counter-offensive that impressed the whole world, but it is also, unfortunately, a place of mass crimes committed by the Russian army on our territory against our people", said Kuleba.
The latest trip is Baerbock's third to the war-torn country since Russia's invasion.
In May, she became the first senior German government figure to travel to Ukraine since the conflict began.