KYIV/Moscow: Russian forces pummelled Ukrainian cities from the air, land and sea on Monday, with warnings they were preparing for an assault on the capital Kyiv, as terrified civilians remained trapped in besieged Mariupol, reports AFP.
The relentless fire has pushed more than 1.5 million people across Ukraine's borders as refugees, though many others are displaced internally or trapped in cities being reduced to rubble by Russian bombardment.
"The head of Gostomel, Yuri Illich Prylypko, died while distributing bread to the hungry and medicine to the sick," the city said on its Facebook page.
Prylypko was shot dead along with two others, it said, without specifying when.
"No-one forced him to go under the occupiers' bullets," it said. "He died for his people, for Gostomel. He died a hero."
Gostomel, northwest of Kyiv, is home to the strategic Antonov military airport, which was the site of fierce battles between Ukrainian and Russian forces in the first days of the war.
International sanctions intended to punish Moscow have so far done little to slow the invasion, and Washington said it was now discussing a ban on Russian oil imports with Europe.
On the ground, air sirens sounded in cities across the country, including the capital Kyiv, and intense aerial bombardment continued in the city of Kharkiv, which has endured almost non-stop fire in recent days.
"The enemy continues the offensive operation against Ukraine, focusing on the encirclement of Kyiv, Kharkiv, Chernihiv, Sumy and Mykolayiv," the General Staff of the Armed Forces of Ukraine said in a statement.
Russian forces "began to accumulate resources for the storming of Kyiv", the statement added.
In the south of the country, regional military officials said Russia had shelled the village of Tuzly in the Odessa region from the sea, targeting "crucial infrastructure sites" but causing no injuries.
And Russia's Interfax reported a large explosion that set alight a fuel depot Monday morning in Lugansk, a town held by pro-Russian separatist rebels.
In Kharkiv, Russian fire hit a university and apartment block in the northeastern city, blowing out all the windows and leaving the facade completed blackened and charred.
In the tangle of splintered wood and mangled metal strewn across the ground in front of the building lay several dead bodies next to a car.
The legs of one person, dressed in brown trousers and black boots could be seen next to a blue surgical mask alongside the back of the car, its roof caved in under the weight of rubble.
Ukraine's President Volodymr Zelensky raged against the growing destruction and death toll, accusing Russian troops of "murder, deliberate murder" in an address.
"We will not forgive, we will not forget, we will punish everyone who committed atrocities in this war on our land," he said. "There will be no quiet place on this Earth except the grave."
Meanwhile, Russia on Sunday warned Ukraine's neighbours including NATO member Romania against hosting Kyiv's military aircraft, saying they could end up being involved in an armed conflict.
"We know for sure that Ukrainian combat aircraft have flown to Romania and other neighbouring countries," defence ministry spokesman Igor Konashenkov said in a video briefing.
"The use of the airfield network of these countries for basing Ukrainian military aviation with the subsequent use of force against Russia's army can be regarded as the involvement of these states in an armed conflict," he added.
"It's pure rhetoric designed to divert attention from what is really happening on the ground -- civilians killed, the rules of armed conflict flouted," Romania's Prime Minister Nicolae Ciuca said during a television interview.
Moscow could try all they want to scare Romania, he added, but "we have no reason to feel threatened".
Ciuca raised an incident reported by the Romanian military on February 24, the first day of the conflict, when a Ukrainian fighter jet was intercepted in Romanian airspace and forced to land.
The pilot told the Romanian authorities that the incursion and been due to a technical problem.
His jet was allowed to leave, unarmed, a few days later and the incident had been made public -- "in all transparency" -- precisely to avoid any misunderstanding with Moscow, Ciuca added.
Ukraine on Monday rejected Moscow's offer of humanitarian corridors to Russia and Belarus, Deputy Prime Minister Iryna Vereshchuk said.
"This is not an acceptable option," she said, after Russia proposed safe passage for civilians from Kharkiv, Kyiv, Mariupol and Sumy.
The civilians "aren't going to go to Belarus and then take a plane to Russia".
The Russian army said earlier on Monday it was opening humanitarian corridors from the four Ukrainian cities.
Russian army spokesman Igor Konashenkov said local ceasefires had begun at 0700 GMT to allow civilians to escape.
Fighting was still ongoing Monday in the four -- the capital Kyiv, the second city Kharkhiv in the east, the southeastern port of Mariupol on the Sea of Azov and Sumy, near the eastern border with Russia.