Ukrainian presidential adviser Mykhailo Podolyak said Sunday that Russian forces were "continuously attacking" the encircled Azovstal steel plant in Mariupol on Easter Sunday.
"Orthodox Easter 2022. But right now, RF (the Russian Federation) is continuously attacking the Mariupol Azovstal," he said on Twitter.
"The place where our civilians and military are located is shelled with heavy air bombs and artillery. RF accumulates forces and equipment for the assault. Who gave the order 'not to storm'?"
Russian President Vladimir Putin claimed earlier this week that Russia forces had achieved the "liberation" of Mariupol, but ordered his forces to stop short of taking the Azovstal plant, the last major bastion of Ukrainian defense in the city.
"RF should think about the remnants of its reputation," Podolyak said, urging Russia to announce an Easter truce in Mariupol, open an evacuation corridor for civilians and agree on a "special round of negotiations" for exchanging military forces encircled in the city.
As the barrage of Mariupol continues, the city's sprawling Azovstal steel plant has become one of the last significant holdouts of Ukrainian forces.
The industrial complex is sheltering hundreds of soldiers and civilians -- and supplies are running low.
On Thursday, Ukrainian Deputy Prime Minister Iryna Vereshchuk said there were "about 1,000 civilians and 500 wounded servicemen there."
Yuriy Ryzhenkov, the CEO of the company that owns the plant, told CNN on Thursday that the situation there was "close to a catastrophe."