
Russia and Ukraine traded blame for ceasefire breaches for a second day as a fresh attempt to evacuate Ukraine citizens from port city of Mariupol failed second time. More than 1.5 million people have fled Ukraine after Russia invaded the country on February 24.
The United Nations has already called Ukraine crisis "Europe's fastest-growing refugee crisis since World War 2"
Pope Francis on Sunday deplored the "rivers of blood and tears" flowing in Ukraine, as Washington cited "very credible reports" that Russia committed war crimes by deliberately attacking civilians.
Hundreds of civilians have been killed and thousands wounded, with hundreds of thousands of mostly women and children pouring into neighbouring countries such as Poland, Romania or Moldova for refuge.
After the West imposed unprecedented sanctions against businesses, banks and billionaires in a bid to choke off the Russian economy, US-based card payment giants Visa and Mastercard were the latest companies to announce they would suspend operations in Russia.
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World leaders vowed further punitive action if Vladimir Putin failed to change course but the Russian leader has equated global sanctions with a declaration of war and has warned that Kyiv is "putting in question the future of Ukrainian statehood".
With a wary eye on Russia's nuclear stocks, NATO allies have so far rebuffed Ukraine's calls for a no-fly zone. Putin has threatened "colossal and catastrophic consequences not only for Europe but also the whole world" if a no-fly zone is set up.
In the latest sign that sanctions were biting, Moscow said Sunday that retailers in Russia will restrict sales of essential goods including bread, rice and flour to limit black market speculation.
Cracking down on dissent at home, Russia detained around 2,500 people across the country for staging protests against its military assault on Ukraine.
The Ukrainian military said Sunday it was engaged in "fierce battles" with Russian forces for the control of borders at the southern city of Mykolaiv and Chernihiv in the north.
"The main efforts are focused on defending the city of Mariupol," it said in a Facebook post, adding an operation by Ukrainian forces was also underway in the eastern part of the Donetsk region.
'Bodies everywhere'
Efforts Saturday to get people out of Mariupol -- one of the most ferocious scenes of war -- collapsed almost immediately with both sides accusing each other of breaching a ceasefire agreement.
A fresh attempt on Sunday again failed.
The strategic city of Mariupol on the Azov Sea has for days been under siege and without electricity, food and water, with stop-start ceasefires.
In a telephone call with French President Emmanuel Macron, Putin blamed Kyiv for not keeping to "agreements reached on this acute humanitarian issue," the Kremlin said.
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But the governor of the eastern region Donetsk, Pavlo Kirilenko, said "the column to evacuate the population could not leave Mariupol... because the Russians regrouped their forces and started to bombard the city."
"It is extremely dangerous to get people out in these conditions," he said, adding that humanitarian aid from Zaporozhzhia also could not reach the people.
Very few refugees from the port city made it out on Saturday, but one family -- who did not give their names -- arrived in the central city of Dnipro and recounted their harrowing experience.
"We stayed in the basement for seven days with no heating, electricity or internet and ran out of food and water. We think we might be the only people to get out," one said.
"On the road, we saw there were bodies everywhere, Russians and Ukrainians. There was so much damage to the city. We saw that people had been buried in their basements."
(With inputs from agencies)