Kyiv has accused Moscow of indiscriminately targeting civilians as well as key infrastructure, threatening the winter supply of electricity, running water and central heating.
"We don't talk about the collapse, but it can happen ... at any second (because) Russian rockets can destroy our critical infrastructure in Kyiv," Vitali Klitschko said, adding that there was currently a 30% deficit in energy in the capital.
"It's pretty cold in Ukraine right now... living without electricity and heating is almost impossible. The situation is critical. We are fighting to survive," he said on the sidelines of the World Economic Forum (WEF) annual meeting in Davos.
Former world heavyweight boxing champions Vitali and Wladimir are part of a broader high-level business and political Ukrainian delegation attending the WEF summit.
"It is important not to hesitate to give us weapons that we so need, but to deliver them the sooner the better otherwise we will continue to lose our infrastructure and most importantly our best men," Wladimir Klitschko said, adding that they expected an escalation in the north of Ukraine from Belarus.
