Russia's war in Ukraine has pushed global displacement numbers above 100 million for the first time, and the UN warned Thursday the resulting hunger crisis could force many more to flee.

Efforts to address the global food crisis, which has been dramatically aggravated by Russia's invasion of Ukraine, is "of paramount importance... to prevent a larger number of people moving", the United Nations refugee chief Filippo Grandi told reporters.

"If you ask me how many... I don't know, but it will be pretty big numbers."