De Croo, a former prime minister of Belgium, told the BBC: “This winter is going to be the toughest one since the war”.
He said Ukraine started “from a very weak base going into this winter”. He added the UN were “very, very worried… about what this winter could become.”
The concerns are driven by what De Croo said was Russia’s “very systematic” targeting of civilian and energy infrastructure.
“This is petrol stations, it’s shopping malls, it’s business centres, but it’s especially energy infrastructure, energy transmission lines, and so on. There is absolutely no justification for that,” he said.
This could lead a “worst-case scenario” where people struggled to access energy to run heating, and water and sewage systems stopped working.
“With the temperatures that you would get here that would lead to circumstances which would be really close to humanitarian catastrophe,” De Croo said.
Winter temperatures in Ukraine can drop to -20C.
If power supplies and critical infrastructure were severely damaged it could lead to “quite some human suffering”, De Croo said.
Under efforts to prepare Ukraine for winter the UN Development Programme is helping to rebuild parts of its energy system that were damaged last winter. It is also establishing more sustainable and decentralised energy plants, which are less vulnerable to attack.
De Croo said completing the difficult and dangerous work was “almost an impossible task”.
“They are reconstructing these sites under constant, constant air alarms. And they know that they are working at a site which is a target,” he said. “So you try to reconstruct, but part of your day you can’t work because it’s just too dangerous.”
