A protracted war in Ukraine, which appears to be a growing possibility, could lead to years of disastrous humanitarian consequences, says United Nations High Commissioner for Refugees Filippo Grandi.

“In our experience as a humanitarian agency, these are the wars that are the most difficult to deal with in terms of humanitarian consequences,” Grandi said in a CBC interview on Sunday.

According to UNHCR figures, nearly 4.4 million Ukrainians have fled their country since the Russian invasion began six weeks ago. That’s about 10 per cent of the country’s total population.

“It was like an ocean of people, a river of people moving out of Ukraine into neighbouring countries,” Grandi said of the exodus.

“The most heartbreaking scenes were the separations between men and their families because men were staying behind to fight. And I had never seen anything like this.”

Most Ukrainian refugees have fled to neighbouring Poland, which has struggled to cope with the sudden and massive wave of people in need of shelter, health care and other basic services.

The UNHCR recently opened a temporary office in Kraków to help that city, which has taken in some 150,000 Ukrainians.

Grandi told CBC Europe’s response to the crisis demonstrates that the continent has the ability to welcome refugees, if not always the desire.

“Now the U.S. is back with a big program, which is great, but if it hadn’t been for Canada staying the course on resettlement … we would have maybe lost the capacity to do this for many vulnerable people. And that deserves glowing words.”

Grandi also noted a shift in the crisis facing Afghanistan. He said humanitarian agencies are now focusing largely on ensuring people still in the country can live safely, rather than facilitating more departures.

He said international groups must pressure the Islamic Emirate of Afghanistan (IEA) to improve its stance on humanitarian issues, even in the face of recent setbacks — such as the move to once again ban girls from attending high school.

“The response to that must be continuous engagement,” Grandi said.

“We can’t let Afghanistan go because if Afghanistan collapses as a state … then we will have another colossal humanitarian emergency on our hands.”