The World Health Organisation has warned of "life-threatening" consequences in Ukraine and estimates that millions could leave their homes as a result.
The World Health Organization's Europe chief said he is "saddened and actually outraged" over the damage inflicted upon healthcare facilities in Ukraine by Russian forces.
Dr Hans Kluge, the WHO Regional Director for Europe, made the comments Thursday during a visit to hospitals in Dnipro, eastern Ukraine, including a psychiatric hospital and a rehabilitation centre.
"As of today, WHO has reported objectively above 700 attacks on healthcare. This is a very clear breach of international law. Health should never be a target," said Kluge.
"The winter will be a threat for millions and millions of Ukraine people. I have seen it. In fact, now the temperature is hovering around zero degrees celsius, but soon it will plummet down to -20.
"Right now there is a blackout in the whole city and the whole oblast. How can a hospital function without electricity? How can maternity wards function without incubators, vaccine storage, without fridges?" he added.
During the visit the WHO team also donated a car and a generator to help medical staff facing power outages during continued Russian bombardments.
Ukraine struggled Thursday to repair its battered power and water services after Russia targeted the electricity grid with dozens of cruise missiles and temperatures plunged.
The Ukrainian energy system is on the brink of collapse and millions have been subjected to emergency blackouts for weeks due to systematic Russian bombardments of the grid.
Kyiv Mayor Vitali Klitschko said more than two-thirds of the capital was still cut off on Thursday despite municipal workers in the capital restoring some water service overnight.
"Seventy per cent of the capital remains without electricity," Klitschko said. "Energy companies are making every effort to return it as soon as possible." he added.
About 50 per cent of the central Dnipropetrovsk region has electricity, governor Valentyn Reznichenko said.
"The energy supply situation is complicated. So shutdowns will continue in the region to reduce the pressure on the grid as much as possible," Reznichenko warned.
Repair work was ongoing elsewhere, including in the Rivne, Cherkasy, Kirovograd and Zhytomyr regions, officials said.