An extra 45 million people could face acute hunger if the Middle East war rages on beyond June, swelling the number worldwide to a "terrible" high, the United Nations warned Tuesday.

The war, now in its third week, and its shockwaves on food and fuel costs could price families out of staple foods far beyond the region, the UN's World Food Programme said.

"The escalating humanitarian fallout from the conflict in the Middle East is growing more concerning by the day," warned WFP deputy executive director Carl Skau.

"Our analysis projects that if the Middle East conflict continues through June," and oil prices remain above $100 a barrel, "an additional 45 million people could be pushed into acute hunger by price rises," he told a Geneva press conference.

"This would take global hunger levels to an all-time record, and it's a terrible, terrible prospect," he said, with a nearly 320 million people — already a huge number — currently acutely food insecure.

"Really it is again taking this to a whole other level," said Skau.

"The consequences are falling on the world's most vulnerable people who are already living in dire conditions. They do not have the margins to cope with a new jump in living costs." 

Skau called for countries to make more humanitarian resources available.